From c02dba0fa0df3a1ce4d49fd6c281a136974486d6 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Wed, 6 Oct 2021 19:25:16 +0530
Subject: [PATCH 01/20] add infix to postfix converter algorithm

---
 misc/infix_to_postfix.c | 96 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 misc/infix_to_postfix.c

diff --git a/misc/infix_to_postfix.c b/misc/infix_to_postfix.c
new file mode 100644
index 0000000000..5edaf97994
--- /dev/null
+++ b/misc/infix_to_postfix.c
@@ -0,0 +1,96 @@
+//infix to postfix
+#include<stdio.h>
+#include<string.h>
+#include<ctype.h>
+#include<process.h>
+
+char stack[10];
+int top=-1;
+void push(char opd)
+{
+	if(top == 9)
+	{
+		printf("Stack overflow...");
+		exit(0);
+	}
+	top++;
+	stack[top]=opd;
+}
+char pop()
+{
+	char item;
+	if(top == -1)
+	{
+		printf("Stack overflow...");
+		exit(0);
+	}
+	item=stack[top];
+	top--;
+	return item;
+}
+
+int isEmpty()
+{
+	if(top == -1)
+		return 1;
+	return 0;
+}
+
+char Top()
+{
+	return stack[top];
+}
+
+int priority(char opd)
+{
+	if(opd == '+' || opd == '-')
+		return 0;
+	else if(opd == '/' || opd == '*' || opd == '%')
+		return 1;
+	else
+		return -1;
+}
+
+void main()
+{
+	char inf[25], post[25];
+	printf("Enter Infix: ");
+	scanf("%s", inf);
+	int i, j=0;
+	for(i=0; i < strlen(inf); i++)
+	{
+		if(isalnum(inf[i]))
+		{
+			post[j] = inf[i];
+			j++;
+		}
+		else if(inf[i] == '(')
+			push(inf[i]);
+		else if(inf[i] == ')')
+		{
+			while(Top() != '(')
+			{
+				post[j] = pop();
+				j++;
+			}
+			pop();
+		}
+		else
+		{
+			while( (!isEmpty()) && (priority(inf[i]) <= priority(Top())) )
+			{
+				post[j] = pop();
+				j++;
+			}
+			push(inf[i]);
+		}
+	}
+	while(!isEmpty())
+	{
+		post[j] = pop();
+		j++;
+	}
+	post[j] = '\0';
+	printf("Postfix: %s", post);
+}
+

From 1d0d7126d3192ef93c48133c05f8a190ad152934 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Thu, 7 Oct 2021 20:20:26 +0530
Subject: [PATCH 02/20] docs: documentation changes

---
 conversions/infix_to_postfix2.c | 140 ++++++++++++++++++++++++++++++++
 misc/infix_to_postfix.c         |  96 ----------------------
 2 files changed, 140 insertions(+), 96 deletions(-)
 create mode 100644 conversions/infix_to_postfix2.c
 delete mode 100644 misc/infix_to_postfix.c

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
new file mode 100644
index 0000000000..b8dab70a55
--- /dev/null
+++ b/conversions/infix_to_postfix2.c
@@ -0,0 +1,140 @@
+/**
+ * @file
+ * @brief infix to postfix converter
+ * @details
+ * The input infix expression is of type string upto 24 characters.
+ * 
+ * Supported operations- '+', '-', '/', '*', '%'
+ *
+ * @author [Kumar Yash](https://github.com/kumaryash18)
+ * @see infix_to_postfix.c
+ */
+ 
+#include<stdio.h>	// for printf() and scanf()
+#include<string.h>	// for strlen()
+#include<ctype.h>	// for isalnum()
+#include<process.h>	// for exit()
+
+/**
+ * @brief array implementation of stack using structure
+ */
+struct Stack {
+	char stack[10];	//< array stack
+	int top;		//< stores index of top element
+};
+struct Stack st;	// global declaration of stack st
+
+/**
+ * @brief Function to push '(' and operators from infix expression
+ * @param opd- character to be pushed in stack
+ * @returns void
+ */
+void push(char opd) {
+	if(st.top == 9)		// overflow condition
+	{
+		printf("Stack overflow...");
+		exit(0);
+	}
+	st.top++;
+	st.stack[st.top] = opd;
+}
+
+/**
+ * @brief Function to pop operators and '('
+ * @returns popped character
+ */
+char pop() {
+	char item;
+	if(st.top == -1)	// underflow condition
+	{
+		printf("Stack underflow...");
+		exit(0);
+	}
+	item = st.stack[st.top];
+	st.top--;
+	return item;
+}
+
+/**
+ * @brief Function to check whether stack is empty or not
+ * @returns `true` if stack is empty
+ * @returns `false` if stack is not empty
+ */
+int isEmpty() {
+	if(st.top == -1)
+		return 1;
+	return 0;
+}
+
+/**
+ * @brief Function to get top of stack
+ * @returns top of stack
+ */
+char Top() {
+	return st.stack[st.top];
+}
+
+/**
+ * @brief Function to check priority of operators
+ * @param opd- operator whose priority is to be checked
+ * @returns 0 if operator is '+' or '-'
+ * @returns 1 if operator is '/' or '*' or '%'
+ * @returns -1 otherwise
+ */
+int priority(char opd) {
+	if(opd == '+' || opd == '-')
+		return 0;
+	else if(opd == '/' || opd == '*' || opd == '%')
+		return 1;
+	else
+		return -1;
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+	st.top = -1;				// represents empty stack
+	char inf[25], post[25];
+	printf("Enter Infix: ");
+	scanf("%s", inf);			// input infix expression
+	int i, j=0;
+	for(i=0; i < strlen(inf); i++)
+	{
+		if(isalnum(inf[i]))		// if scanned element is an alphabet or number
+		{
+			post[j] = inf[i];	// append in postfix expression
+			j++;
+		}
+		else if(inf[i] == '(')	// if scanned element is opening parentheses
+			push(inf[i]);		// push on stack.
+		else if(inf[i] == ')')	// if scanned element is closing parentheses,
+		{
+			while(Top() != '(')	// pop elements from stack and append in postfix expression
+			{					// until opening parentheses becomes top
+				post[j] = pop();
+				j++;
+			}
+			pop();				// pop opening parentheses
+		}
+		else					// if scanned element is an operator
+		{
+			while( (!isEmpty()) && (priority(inf[i]) <= priority(Top())) )	// pop and append until stack becomes
+			{																// empty or priority of top operator
+				post[j] = pop();											// becomes smaller than scanned operator
+				j++;														// '(' has priority -1
+			}
+			push(inf[i]);		// push the scanned operator
+		}
+	}
+	while(!isEmpty())			// pop and append residual operators from stack
+	{
+		post[j] = pop();
+		j++;
+	}
+	post[j] = '\0';
+	printf("Postfix: %s", post);	// print postfix expression
+	return 0;
+}
+
diff --git a/misc/infix_to_postfix.c b/misc/infix_to_postfix.c
deleted file mode 100644
index 5edaf97994..0000000000
--- a/misc/infix_to_postfix.c
+++ /dev/null
@@ -1,96 +0,0 @@
-//infix to postfix
-#include<stdio.h>
-#include<string.h>
-#include<ctype.h>
-#include<process.h>
-
-char stack[10];
-int top=-1;
-void push(char opd)
-{
-	if(top == 9)
-	{
-		printf("Stack overflow...");
-		exit(0);
-	}
-	top++;
-	stack[top]=opd;
-}
-char pop()
-{
-	char item;
-	if(top == -1)
-	{
-		printf("Stack overflow...");
-		exit(0);
-	}
-	item=stack[top];
-	top--;
-	return item;
-}
-
-int isEmpty()
-{
-	if(top == -1)
-		return 1;
-	return 0;
-}
-
-char Top()
-{
-	return stack[top];
-}
-
-int priority(char opd)
-{
-	if(opd == '+' || opd == '-')
-		return 0;
-	else if(opd == '/' || opd == '*' || opd == '%')
-		return 1;
-	else
-		return -1;
-}
-
-void main()
-{
-	char inf[25], post[25];
-	printf("Enter Infix: ");
-	scanf("%s", inf);
-	int i, j=0;
-	for(i=0; i < strlen(inf); i++)
-	{
-		if(isalnum(inf[i]))
-		{
-			post[j] = inf[i];
-			j++;
-		}
-		else if(inf[i] == '(')
-			push(inf[i]);
-		else if(inf[i] == ')')
-		{
-			while(Top() != '(')
-			{
-				post[j] = pop();
-				j++;
-			}
-			pop();
-		}
-		else
-		{
-			while( (!isEmpty()) && (priority(inf[i]) <= priority(Top())) )
-			{
-				post[j] = pop();
-				j++;
-			}
-			push(inf[i]);
-		}
-	}
-	while(!isEmpty())
-	{
-		post[j] = pop();
-		j++;
-	}
-	post[j] = '\0';
-	printf("Postfix: %s", post);
-}
-

From 32dd3e81b950ab2684b641acfb3265ac6eab0552 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Thu, 7 Oct 2021 22:02:53 +0530
Subject: [PATCH 03/20] docs: documentation changes

---
 conversions/infix_to_postfix2.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index b8dab70a55..58f7315e47 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -10,10 +10,10 @@
  * @see infix_to_postfix.c
  */
  
-#include<stdio.h>	// for printf() and scanf()
-#include<string.h>	// for strlen()
-#include<ctype.h>	// for isalnum()
-#include<process.h>	// for exit()
+#include<stdio.h>	/// for IO operations
+#include<string.h>	/// for strlen()
+#include<ctype.h>	/// for isalnum()
+#include<process.h>	/// for exit()
 
 /**
  * @brief array implementation of stack using structure

From 8566c2eece7ab575be4ad4280ed3c50aae136253 Mon Sep 17 00:00:00 2001
From: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Date: Thu, 7 Oct 2021 16:34:26 +0000
Subject: [PATCH 04/20] updating DIRECTORY.md

---
 DIRECTORY.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/DIRECTORY.md b/DIRECTORY.md
index 0b22b5b92b..0c653fd22c 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -26,6 +26,7 @@
   * [Hexadecimal To Octal](https://github.com/TheAlgorithms/C/blob/master/conversions/hexadecimal_to_octal.c)
   * [Hexadecimal To Octal2](https://github.com/TheAlgorithms/C/blob/master/conversions/hexadecimal_to_octal2.c)
   * [Infix To Postfix](https://github.com/TheAlgorithms/C/blob/master/conversions/infix_to_postfix.c)
+  * [Infix To Postfix2](https://github.com/TheAlgorithms/C/blob/master/conversions/infix_to_postfix2.c)
   * [Int To String](https://github.com/TheAlgorithms/C/blob/master/conversions/int_to_string.c)
   * [Octal To Binary](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_binary.c)
   * [Octal To Decimal](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_decimal.c)

From 45d92c5cc14969047bcaf64900922d843644569e Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Fri, 8 Oct 2021 13:35:29 +0530
Subject: [PATCH 05/20] docs: documentation changes

---
 conversions/infix_to_postfix2.c | 80 ++++++++++++++++-----------------
 1 file changed, 39 insertions(+), 41 deletions(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index 58f7315e47..d683ce6e74 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -19,10 +19,10 @@
  * @brief array implementation of stack using structure
  */
 struct Stack {
-	char stack[10];	//< array stack
-	int top;		//< stores index of top element
+	char stack[10];		///< array stack
+	int top;			///< stores index of top element
 };
-struct Stack st;	// global declaration of stack st
+struct Stack st;		///< global declaration of stack st
 
 /**
  * @brief Function to push '(' and operators from infix expression
@@ -30,8 +30,7 @@ struct Stack st;	// global declaration of stack st
  * @returns void
  */
 void push(char opd) {
-	if(st.top == 9)		// overflow condition
-	{
+	if(st.top == 9)	{		// overflow condition
 		printf("Stack overflow...");
 		exit(0);
 	}
@@ -44,9 +43,8 @@ void push(char opd) {
  * @returns popped character
  */
 char pop() {
-	char item;
-	if(st.top == -1)	// underflow condition
-	{
+	char item;				///< to store popped value to be returned
+	if(st.top == -1) {		// underflow condition
 		printf("Stack underflow...");
 		exit(0);
 	}
@@ -61,8 +59,9 @@ char pop() {
  * @returns `false` if stack is not empty
  */
 int isEmpty() {
-	if(st.top == -1)
+	if(st.top == -1) {
 		return 1;
+	}
 	return 0;
 }
 
@@ -82,12 +81,15 @@ char Top() {
  * @returns -1 otherwise
  */
 int priority(char opd) {
-	if(opd == '+' || opd == '-')
+	if(opd == '+' || opd == '-') {
 		return 0;
-	else if(opd == '/' || opd == '*' || opd == '%')
+	}
+	else if(opd == '/' || opd == '*' || opd == '%') {
 		return 1;
-	else
+	}
+	else {
 		return -1;
+	}
 }
 
 /**
@@ -95,46 +97,42 @@ int priority(char opd) {
  * @returns 0 on exit
  */
 int main() {
-	st.top = -1;				// represents empty stack
-	char inf[25], post[25];
+	st.top = -1;						// represents empty stack
+	char inf[25];						///< to store the input infix expression
+	char post[25];						///< to store the postfix expression
 	printf("Enter Infix: ");
-	scanf("%s", inf);			// input infix expression
-	int i, j=0;
-	for(i=0; i < strlen(inf); i++)
-	{
-		if(isalnum(inf[i]))		// if scanned element is an alphabet or number
-		{
-			post[j] = inf[i];	// append in postfix expression
+	scanf("%s", inf);					// input infix expression
+	int i;								///< loop iterator
+	int j=0;							///< keeps track of end of postfix string
+	for(i=0; i < strlen(inf); i++) {
+		if(isalnum(inf[i]))	{			// if scanned element is an alphabet or number
+			post[j] = inf[i];			// append in postfix expression
 			j++;
 		}
-		else if(inf[i] == '(')	// if scanned element is opening parentheses
-			push(inf[i]);		// push on stack.
-		else if(inf[i] == ')')	// if scanned element is closing parentheses,
-		{
-			while(Top() != '(')	// pop elements from stack and append in postfix expression
-			{					// until opening parentheses becomes top
-				post[j] = pop();
+		else if(inf[i] == '(') {		// if scanned element is opening parentheses
+			push(inf[i]);				// push on stack.
+		}
+		else if(inf[i] == ')') {		// if scanned element is closing parentheses,
+			while(Top() != '(') {		// pop elements from stack and append in postfix expression
+				post[j] = pop();		// until opening parentheses becomes top.
 				j++;
 			}
-			pop();				// pop opening parentheses
+			pop();						// pop opening parentheses
 		}
-		else					// if scanned element is an operator
-		{
-			while( (!isEmpty()) && (priority(inf[i]) <= priority(Top())) )	// pop and append until stack becomes
-			{																// empty or priority of top operator
-				post[j] = pop();											// becomes smaller than scanned operator
-				j++;														// '(' has priority -1
-			}
-			push(inf[i]);		// push the scanned operator
+		else {							// if scanned element is an operator
+			while( (!isEmpty()) && (priority(inf[i]) <= priority(Top())) ) {	// pop and append until stack becomes
+				post[j] = pop();												// empty or priority of top operator
+				j++;															// becomes smaller than scanned operator
+			}																	// '(' has priority -1
+			push(inf[i]);				// push the scanned operator
 		}
 	}
-	while(!isEmpty())			// pop and append residual operators from stack
-	{
+	while(!isEmpty()) {					// pop and append residual operators from stack
 		post[j] = pop();
 		j++;
 	}
-	post[j] = '\0';
-	printf("Postfix: %s", post);	// print postfix expression
+	post[j] = '\0';						// end postfix string with null character
+	printf("Postfix: %s", post);		// print postfix expression
 	return 0;
 }
 

From b0fa88682951433084c15de3e6d1522ae0f147f5 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Mon, 11 Oct 2021 14:39:11 +0530
Subject: [PATCH 06/20] fix: continuous integration

---
 conversions/infix_to_postfix2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index d683ce6e74..698c5fbe72 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -13,7 +13,7 @@
 #include<stdio.h>	/// for IO operations
 #include<string.h>	/// for strlen()
 #include<ctype.h>	/// for isalnum()
-#include<process.h>	/// for exit()
+#include<stdlib.h>	/// for exit()
 
 /**
  * @brief array implementation of stack using structure

From 71a73531e02fc8881a522d1105faa8b619ebde6a Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Wed, 13 Oct 2021 16:13:07 +0530
Subject: [PATCH 07/20] [test, docs]: add test case, documentation changes

---
 conversions/infix_to_postfix2.c | 69 +++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 25 deletions(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index 698c5fbe72..1ad04f95e0 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -1,19 +1,20 @@
 /**
  * @file
  * @brief infix to postfix converter
+ * Wikipedia- [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm)
  * @details
  * The input infix expression is of type string upto 24 characters.
- * 
  * Supported operations- '+', '-', '/', '*', '%'
- *
  * @author [Kumar Yash](https://github.com/kumaryash18)
  * @see infix_to_postfix.c
  */
  
-#include<stdio.h>	/// for IO operations
-#include<string.h>	/// for strlen()
-#include<ctype.h>	/// for isalnum()
-#include<stdlib.h>	/// for exit()
+#include <stdio.h>	/// for IO operations
+#include <string.h>	/// for strlen(), strcmpi()
+#include <ctype.h>	/// for isalnum()
+#include <stdlib.h>	/// for exit()
+#include <stdint.h>	/// for uint16_t, int16_t
+#include <assert.h>	/// for assert
 
 /**
  * @brief array implementation of stack using structure
@@ -25,8 +26,8 @@ struct Stack {
 struct Stack st;		///< global declaration of stack st
 
 /**
- * @brief Function to push '(' and operators from infix expression
- * @param opd- character to be pushed in stack
+ * @brief Function to push on stack
+ * @param opd character to be pushed in stack
  * @returns void
  */
 void push(char opd) {
@@ -39,7 +40,7 @@ void push(char opd) {
 }
 
 /**
- * @brief Function to pop operators and '('
+ * @brief Function to pop from stack
  * @returns popped character
  */
 char pop() {
@@ -58,7 +59,7 @@ char pop() {
  * @returns `true` if stack is empty
  * @returns `false` if stack is not empty
  */
-int isEmpty() {
+uint16_t isEmpty() {
 	if(st.top == -1) {
 		return 1;
 	}
@@ -75,16 +76,16 @@ char Top() {
 
 /**
  * @brief Function to check priority of operators
- * @param opd- operator whose priority is to be checked
+ * @param opr operator whose priority is to be checked
  * @returns 0 if operator is '+' or '-'
  * @returns 1 if operator is '/' or '*' or '%'
  * @returns -1 otherwise
  */
-int priority(char opd) {
-	if(opd == '+' || opd == '-') {
+int16_t priority(char opr) {
+	if(opr == '+' || opr == '-') {
 		return 0;
 	}
-	else if(opd == '/' || opd == '*' || opd == '%') {
+	else if(opr == '/' || opr == '*' || opr == '%') {
 		return 1;
 	}
 	else {
@@ -93,18 +94,15 @@ int priority(char opd) {
 }
 
 /**
- * @brief Main function
- * @returns 0 on exit
+ * @brief Function to convert infix to postfix expression
+ * @param inf the input infix expression
+ * @returns output postfix expression
  */
-int main() {
-	st.top = -1;						// represents empty stack
-	char inf[25];						///< to store the input infix expression
-	char post[25];						///< to store the postfix expression
-	printf("Enter Infix: ");
-	scanf("%s", inf);					// input infix expression
+char *convert(char inf[]) {
+	static char post[25];				///< to store the postfix expression
 	int i;								///< loop iterator
-	int j=0;							///< keeps track of end of postfix string
-	for(i=0; i < strlen(inf); i++) {
+	int j = 0;							///< keeps track of end of postfix string
+	for(i = 0; i < strlen(inf); i++) {
 		if(isalnum(inf[i]))	{			// if scanned element is an alphabet or number
 			post[j] = inf[i];			// append in postfix expression
 			j++;
@@ -132,7 +130,28 @@ int main() {
 		j++;
 	}
 	post[j] = '\0';						// end postfix string with null character
-	printf("Postfix: %s", post);		// print postfix expression
+	return post;
+}
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    /* check sample test case
+	   input- "(A/(B-C)*D+E)"
+	   expected output- "ABC-/D*E+"
+	 */
+	assert(strcmpi(convert("(A/(B-C)*D+E)"), "ABC-/D*E+") == 0); 			// this ensures that the algorithm works as expected
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+	st.top = -1;						// initialize
+	test();								// run self-test implementations
 	return 0;
 }
 

From 6e4f228ba786840e13ebfd8436bdf3efb19aff01 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Wed, 13 Oct 2021 16:38:19 +0530
Subject: [PATCH 08/20] docs: documentation changes

---
 conversions/infix_to_postfix2.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index 1ad04f95e0..875c9390f8 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -152,6 +152,10 @@ static void test() {
 int main() {
 	st.top = -1;						// initialize
 	test();								// run self-test implementations
+	char inf[25];						///< to store input infix expression
+	printf("Enter infix: ");
+	scanf("%s", inf);
+	printf("Postfix: %s", convert(inf));
 	return 0;
 }
 

From 9fae7a02a58ddd7423a02b6f76dbf7ab8120d6fc Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Wed, 13 Oct 2021 16:52:16 +0530
Subject: [PATCH 09/20] fix: continuous integration

---
 conversions/infix_to_postfix2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index 875c9390f8..a580b857dc 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -10,7 +10,7 @@
  */
  
 #include <stdio.h>	/// for IO operations
-#include <string.h>	/// for strlen(), strcmpi()
+#include <string.h>	/// for strlen(), strcmp()
 #include <ctype.h>	/// for isalnum()
 #include <stdlib.h>	/// for exit()
 #include <stdint.h>	/// for uint16_t, int16_t
@@ -142,7 +142,7 @@ static void test() {
 	   input- "(A/(B-C)*D+E)"
 	   expected output- "ABC-/D*E+"
 	 */
-	assert(strcmpi(convert("(A/(B-C)*D+E)"), "ABC-/D*E+") == 0); 			// this ensures that the algorithm works as expected
+	assert(strcmp(convert("(A/(B-C)*D+E)"), "ABC-/D*E+") == 0); 			// this ensures that the algorithm works as expected
 }
 
 /**

From dfa503489e929f81fdcb135141bd86ada5cf9033 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Wed, 13 Oct 2021 22:43:15 +0530
Subject: [PATCH 10/20] docs: documentation changes

---
 conversions/infix_to_postfix2.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index a580b857dc..a9e5e3ea86 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -1,7 +1,7 @@
 /**
  * @file
  * @brief infix to postfix converter
- * Wikipedia- [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm)
+ * Reference- [infix to postfix converter](https://www.includehelp.com/c/infix-to-postfix-conversion-using-stack-with-c-program.aspx)
  * @details
  * The input infix expression is of type string upto 24 characters.
  * Supported operations- '+', '-', '/', '*', '%'
@@ -21,7 +21,7 @@
  */
 struct Stack {
 	char stack[10];		///< array stack
-	int top;			///< stores index of top element
+	int top;		///< stores index of top element
 };
 struct Stack st;		///< global declaration of stack st
 
@@ -33,7 +33,7 @@ struct Stack st;		///< global declaration of stack st
 void push(char opd) {
 	if(st.top == 9)	{		// overflow condition
 		printf("Stack overflow...");
-		exit(0);
+		exit(1);
 	}
 	st.top++;
 	st.stack[st.top] = opd;
@@ -47,7 +47,7 @@ char pop() {
 	char item;				///< to store popped value to be returned
 	if(st.top == -1) {		// underflow condition
 		printf("Stack underflow...");
-		exit(0);
+		exit(1);
 	}
 	item = st.stack[st.top];
 	st.top--;
@@ -56,8 +56,8 @@ char pop() {
 
 /**
  * @brief Function to check whether stack is empty or not
- * @returns `true` if stack is empty
- * @returns `false` if stack is not empty
+ * @returns 1 if stack is empty
+ * @returns 0 if stack is not empty
  */
 uint16_t isEmpty() {
 	if(st.top == -1) {
@@ -150,12 +150,11 @@ static void test() {
  * @returns 0 on exit
  */
 int main() {
-	st.top = -1;						// initialize
-	test();								// run self-test implementations
+	st.top = -1;			/// initialize
+	test();				/// run self-test implementations
 	char inf[25];						///< to store input infix expression
 	printf("Enter infix: ");
 	scanf("%s", inf);
 	printf("Postfix: %s", convert(inf));
 	return 0;
 }
-

From b34b396a2f9f79bf6b12233d792ebf07a8dc2f45 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Thu, 14 Oct 2021 15:50:04 +0530
Subject: [PATCH 11/20] docs: documentation changes

---
 conversions/infix_to_postfix2.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index a9e5e3ea86..385774d157 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -1,7 +1,6 @@
 /**
  * @file
- * @brief infix to postfix converter
- * Reference- [infix to postfix converter](https://www.includehelp.com/c/infix-to-postfix-conversion-using-stack-with-c-program.aspx)
+ * @brief [Infix to Postfix converter](https://www.includehelp.com/c/infix-to-postfix-conversion-using-stack-with-c-program.aspx) implementation
  * @details
  * The input infix expression is of type string upto 24 characters.
  * Supported operations- '+', '-', '/', '*', '%'
@@ -21,13 +20,13 @@
  */
 struct Stack {
 	char stack[10];		///< array stack
-	int top;		///< stores index of top element
+	int top;		///< stores index of the top element
 };
 struct Stack st;		///< global declaration of stack st
 
 /**
- * @brief Function to push on stack
- * @param opd character to be pushed in stack
+ * @brief Function to push on the stack
+ * @param opd character to be pushed in the stack
  * @returns void
  */
 void push(char opd) {
@@ -40,11 +39,11 @@ void push(char opd) {
 }
 
 /**
- * @brief Function to pop from stack
+ * @brief Function to pop from the stack
  * @returns popped character
  */
 char pop() {
-	char item;				///< to store popped value to be returned
+	char item;				///< to store the popped value to be returned
 	if(st.top == -1) {		// underflow condition
 		printf("Stack underflow...");
 		exit(1);
@@ -55,9 +54,9 @@ char pop() {
 }
 
 /**
- * @brief Function to check whether stack is empty or not
- * @returns 1 if stack is empty
- * @returns 0 if stack is not empty
+ * @brief Function to check whether the stack is empty or not
+ * @returns 1 if the stack IS empty
+ * @returns 0 if the stack is NOT empty
  */
 uint16_t isEmpty() {
 	if(st.top == -1) {
@@ -67,7 +66,7 @@ uint16_t isEmpty() {
 }
 
 /**
- * @brief Function to get top of stack
+ * @brief Function to get top of the stack
  * @returns top of stack
  */
 char Top() {
@@ -94,7 +93,7 @@ int16_t priority(char opr) {
 }
 
 /**
- * @brief Function to convert infix to postfix expression
+ * @brief Function to convert infix expression to postfix expression
  * @param inf the input infix expression
  * @returns output postfix expression
  */
@@ -152,7 +151,7 @@ static void test() {
 int main() {
 	st.top = -1;			/// initialize
 	test();				/// run self-test implementations
-	char inf[25];						///< to store input infix expression
+	char inf[25];			///< to store input infix expression
 	printf("Enter infix: ");
 	scanf("%s", inf);
 	printf("Postfix: %s", convert(inf));

From f993e0f4071396a8977fad5593c5aa7d6694a592 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Fri, 15 Oct 2021 18:56:54 +0530
Subject: [PATCH 12/20] test: add new test

---
 conversions/infix_to_postfix2.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
index 385774d157..e0f584003b 100644
--- a/conversions/infix_to_postfix2.c
+++ b/conversions/infix_to_postfix2.c
@@ -141,7 +141,12 @@ static void test() {
 	   input- "(A/(B-C)*D+E)"
 	   expected output- "ABC-/D*E+"
 	 */
-	assert(strcmp(convert("(A/(B-C)*D+E)"), "ABC-/D*E+") == 0); 			// this ensures that the algorithm works as expected
+	assert(strcmp(convert("(A/(B-C)*D+E)"), "ABC-/D*E+") == 0); 			/// this ensures that the algorithm works as expected
+	/* input- "7-(2*3+5)*(8-4/2)"
+	   expected output- "723*5+842/-*-"
+	 */
+	assert(strcmp(convert("7-(2*3+5)*(8-4/2)"), "723*5+842/-*-") == 0); 			/// this ensures that the algorithm works as expected
+	printf("All tests have successfully passed!\n");
 }
 
 /**

From ff4aadbcdc981188109ba331b0f4d19c796cff2b Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Sat, 16 Oct 2021 17:37:42 +0530
Subject: [PATCH 13/20] feat: add postfix evaluation algorithm

---
 conversions/infix_to_postfix2.c | 164 --------------------------------
 misc/postfix_evaluation.c       | 121 +++++++++++++++++++++++
 2 files changed, 121 insertions(+), 164 deletions(-)
 delete mode 100644 conversions/infix_to_postfix2.c
 create mode 100644 misc/postfix_evaluation.c

diff --git a/conversions/infix_to_postfix2.c b/conversions/infix_to_postfix2.c
deleted file mode 100644
index e0f584003b..0000000000
--- a/conversions/infix_to_postfix2.c
+++ /dev/null
@@ -1,164 +0,0 @@
-/**
- * @file
- * @brief [Infix to Postfix converter](https://www.includehelp.com/c/infix-to-postfix-conversion-using-stack-with-c-program.aspx) implementation
- * @details
- * The input infix expression is of type string upto 24 characters.
- * Supported operations- '+', '-', '/', '*', '%'
- * @author [Kumar Yash](https://github.com/kumaryash18)
- * @see infix_to_postfix.c
- */
- 
-#include <stdio.h>	/// for IO operations
-#include <string.h>	/// for strlen(), strcmp()
-#include <ctype.h>	/// for isalnum()
-#include <stdlib.h>	/// for exit()
-#include <stdint.h>	/// for uint16_t, int16_t
-#include <assert.h>	/// for assert
-
-/**
- * @brief array implementation of stack using structure
- */
-struct Stack {
-	char stack[10];		///< array stack
-	int top;		///< stores index of the top element
-};
-struct Stack st;		///< global declaration of stack st
-
-/**
- * @brief Function to push on the stack
- * @param opd character to be pushed in the stack
- * @returns void
- */
-void push(char opd) {
-	if(st.top == 9)	{		// overflow condition
-		printf("Stack overflow...");
-		exit(1);
-	}
-	st.top++;
-	st.stack[st.top] = opd;
-}
-
-/**
- * @brief Function to pop from the stack
- * @returns popped character
- */
-char pop() {
-	char item;				///< to store the popped value to be returned
-	if(st.top == -1) {		// underflow condition
-		printf("Stack underflow...");
-		exit(1);
-	}
-	item = st.stack[st.top];
-	st.top--;
-	return item;
-}
-
-/**
- * @brief Function to check whether the stack is empty or not
- * @returns 1 if the stack IS empty
- * @returns 0 if the stack is NOT empty
- */
-uint16_t isEmpty() {
-	if(st.top == -1) {
-		return 1;
-	}
-	return 0;
-}
-
-/**
- * @brief Function to get top of the stack
- * @returns top of stack
- */
-char Top() {
-	return st.stack[st.top];
-}
-
-/**
- * @brief Function to check priority of operators
- * @param opr operator whose priority is to be checked
- * @returns 0 if operator is '+' or '-'
- * @returns 1 if operator is '/' or '*' or '%'
- * @returns -1 otherwise
- */
-int16_t priority(char opr) {
-	if(opr == '+' || opr == '-') {
-		return 0;
-	}
-	else if(opr == '/' || opr == '*' || opr == '%') {
-		return 1;
-	}
-	else {
-		return -1;
-	}
-}
-
-/**
- * @brief Function to convert infix expression to postfix expression
- * @param inf the input infix expression
- * @returns output postfix expression
- */
-char *convert(char inf[]) {
-	static char post[25];				///< to store the postfix expression
-	int i;								///< loop iterator
-	int j = 0;							///< keeps track of end of postfix string
-	for(i = 0; i < strlen(inf); i++) {
-		if(isalnum(inf[i]))	{			// if scanned element is an alphabet or number
-			post[j] = inf[i];			// append in postfix expression
-			j++;
-		}
-		else if(inf[i] == '(') {		// if scanned element is opening parentheses
-			push(inf[i]);				// push on stack.
-		}
-		else if(inf[i] == ')') {		// if scanned element is closing parentheses,
-			while(Top() != '(') {		// pop elements from stack and append in postfix expression
-				post[j] = pop();		// until opening parentheses becomes top.
-				j++;
-			}
-			pop();						// pop opening parentheses
-		}
-		else {							// if scanned element is an operator
-			while( (!isEmpty()) && (priority(inf[i]) <= priority(Top())) ) {	// pop and append until stack becomes
-				post[j] = pop();												// empty or priority of top operator
-				j++;															// becomes smaller than scanned operator
-			}																	// '(' has priority -1
-			push(inf[i]);				// push the scanned operator
-		}
-	}
-	while(!isEmpty()) {					// pop and append residual operators from stack
-		post[j] = pop();
-		j++;
-	}
-	post[j] = '\0';						// end postfix string with null character
-	return post;
-}
-
-/**
- * @brief Self-test implementations
- * @returns void
- */
-static void test() {
-    /* check sample test case
-	   input- "(A/(B-C)*D+E)"
-	   expected output- "ABC-/D*E+"
-	 */
-	assert(strcmp(convert("(A/(B-C)*D+E)"), "ABC-/D*E+") == 0); 			/// this ensures that the algorithm works as expected
-	/* input- "7-(2*3+5)*(8-4/2)"
-	   expected output- "723*5+842/-*-"
-	 */
-	assert(strcmp(convert("7-(2*3+5)*(8-4/2)"), "723*5+842/-*-") == 0); 			/// this ensures that the algorithm works as expected
-	printf("All tests have successfully passed!\n");
-}
-
-/**
- * @brief Main function
- * @returns 0 on exit
- */
-int main() {
-	st.top = -1;			/// initialize
-	test();				/// run self-test implementations
-	char inf[25];			///< to store input infix expression
-	printf("Enter infix: ");
-	scanf("%s", inf);
-	printf("Postfix: %s", convert(inf));
-	return 0;
-}
diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
new file mode 100644
index 0000000000..236b291d93
--- /dev/null
+++ b/misc/postfix_evaluation.c
@@ -0,0 +1,121 @@
+/**
+ * @file
+ * @brief [Postfix evaluation algorithm](https://www.includehelp.com/c/evaluation-of-postfix-expressions-using-stack-with-c-program.aspx) implementation
+ * @details
+ * The input postfix expression is of type string upto 24 characters (single digit numbers only).
+ * Supported operations- '+', '-', '/', '*', '%'
+ * @author [Kumar Yash](https://github.com/kumaryash18)
+ */
+ 
+#include <stdio.h>	/// for IO operations
+#include <string.h>	/// for strlen()
+#include <ctype.h>	/// for isdigit()
+#include <stdlib.h>	/// for exit()
+#include <stdint.h>	/// for int8_t
+#include <assert.h>	/// for assert
+
+/**
+ * @brief array implementation of stack using structure
+ */
+struct Stack {
+	int stack[10];		///< array stack
+	int top;		///< stores index of the top element
+};
+struct Stack st;		///< global declaration of stack st
+
+/**
+ * @brief Function to push on the stack
+ * @param opd number to be pushed in the stack
+ * @returns void
+ */
+void push(int8_t opd) {
+	if(st.top == 9)	{		// overflow condition
+		printf("Stack overflow...");
+		exit(1);
+	}
+	st.top++;
+	st.stack[st.top] = opd;
+}
+
+/**
+ * @brief Function to pop from the stack
+ * @returns popped number
+ */
+int8_t pop() {
+	int8_t item;				///< to store the popped value to be returned
+	if(st.top == -1) {		// underflow condition
+		printf("Stack underflow...");
+		exit(1);
+	}
+	item = st.stack[st.top];
+	st.top--;
+	return item;
+}
+
+/**
+ * @brief Function to evaluate postfix expression
+ * @param post the input postfix expression
+ * @returns evaluated answer
+ */
+int8_t evaluate(char post[]) {
+	int8_t it1;
+	int8_t it2;
+	int8_t temp;
+    int i;
+    for(i = 0; i < strlen(post); i++) {
+		if(isdigit(post[i])) {
+			push(post[i]-'0');
+		}
+		else {
+			it2 = pop();
+			it1 = pop();
+			switch(post[i]) {
+				case '+':
+				temp = it1 + it2; break;
+				case '-':
+				temp = it1 - it2; break;
+				case '*':
+				temp = it1 * it2; break;
+				case '/':
+				temp = it1 / it2; break;
+				case '%':
+				temp = it1 % it2; break;
+				default:
+				printf("Invalid operator"); exit(1);
+			}
+			push(temp);
+		}
+	}
+	return pop();
+}
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    /* check sample test case
+	   input: "4572+-*"
+	   expected output: -16
+	 */
+	assert(evaluate("4572+-*") == -16); 			/// this ensures that the algorithm works as expected
+	/* input: "42+351-*+"
+	   expected output: 18
+	 */
+	assert(evaluate("42+351-*+") == 18); 			/// this ensures that the algorithm works as expected
+	printf("All tests have successfully passed!\n");
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+	st.top = -1;			/// initialize
+	test();				/// run self-test implementations
+	char post[25];			///< to store input postfix expression
+	printf("Enter postfix: ");
+	scanf("%s", post);
+	printf("Evaluated answer: %d", evaluate(post));
+	return 0;
+}

From cb1ac8088696ef3033351933ffae3d04627d19f2 Mon Sep 17 00:00:00 2001
From: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Date: Sat, 16 Oct 2021 12:08:34 +0000
Subject: [PATCH 14/20] updating DIRECTORY.md

---
 DIRECTORY.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/DIRECTORY.md b/DIRECTORY.md
index 0c653fd22c..46c011f911 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -26,7 +26,6 @@
   * [Hexadecimal To Octal](https://github.com/TheAlgorithms/C/blob/master/conversions/hexadecimal_to_octal.c)
   * [Hexadecimal To Octal2](https://github.com/TheAlgorithms/C/blob/master/conversions/hexadecimal_to_octal2.c)
   * [Infix To Postfix](https://github.com/TheAlgorithms/C/blob/master/conversions/infix_to_postfix.c)
-  * [Infix To Postfix2](https://github.com/TheAlgorithms/C/blob/master/conversions/infix_to_postfix2.c)
   * [Int To String](https://github.com/TheAlgorithms/C/blob/master/conversions/int_to_string.c)
   * [Octal To Binary](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_binary.c)
   * [Octal To Decimal](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_decimal.c)
@@ -272,6 +271,7 @@
   * [Palindrome](https://github.com/TheAlgorithms/C/blob/master/misc/palindrome.c)
   * [Pid](https://github.com/TheAlgorithms/C/blob/master/misc/pid.c)
   * [Poly Add](https://github.com/TheAlgorithms/C/blob/master/misc/poly_add.c)
+  * [Postfix Evaluation](https://github.com/TheAlgorithms/C/blob/master/misc/postfix_evaluation.c)
   * [Prime](https://github.com/TheAlgorithms/C/blob/master/misc/prime.c)
   * [Prime Factoriziation](https://github.com/TheAlgorithms/C/blob/master/misc/prime_factoriziation.c)
   * [Prime Seive](https://github.com/TheAlgorithms/C/blob/master/misc/prime_seive.c)

From bbffdf743010ea87d197971f5618589f3be1ebfa Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Mon, 18 Oct 2021 14:31:58 +0530
Subject: [PATCH 15/20] fix: increase stack size

---
 misc/postfix_evaluation.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
index 236b291d93..9f6326baff 100644
--- a/misc/postfix_evaluation.c
+++ b/misc/postfix_evaluation.c
@@ -18,7 +18,7 @@
  * @brief array implementation of stack using structure
  */
 struct Stack {
-	int stack[10];		///< array stack
+	int stack[20];		///< array stack
 	int top;		///< stores index of the top element
 };
 struct Stack st;		///< global declaration of stack st
@@ -29,7 +29,7 @@ struct Stack st;		///< global declaration of stack st
  * @returns void
  */
 void push(int8_t opd) {
-	if(st.top == 9)	{		// overflow condition
+	if(st.top == 19)	{		// overflow condition
 		printf("Stack overflow...");
 		exit(1);
 	}

From ff85f978e43ec4bb3d20dc15133f80b2254fd614 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Wed, 20 Oct 2021 11:11:21 +0530
Subject: [PATCH 16/20] fix: change data type

---
 misc/postfix_evaluation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
index 9f6326baff..ad451eb098 100644
--- a/misc/postfix_evaluation.c
+++ b/misc/postfix_evaluation.c
@@ -18,7 +18,7 @@
  * @brief array implementation of stack using structure
  */
 struct Stack {
-	int stack[20];		///< array stack
+	int8_t stack[20];		///< array stack
 	int top;		///< stores index of the top element
 };
 struct Stack st;		///< global declaration of stack st

From 0a3ac0f07f6309f64e77be8d267f151e0bef6a92 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Sat, 23 Oct 2021 17:26:28 +0530
Subject: [PATCH 17/20] add: parse feature

---
 misc/postfix_evaluation.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
index ad451eb098..faa7993c78 100644
--- a/misc/postfix_evaluation.c
+++ b/misc/postfix_evaluation.c
@@ -2,7 +2,7 @@
  * @file
  * @brief [Postfix evaluation algorithm](https://www.includehelp.com/c/evaluation-of-postfix-expressions-using-stack-with-c-program.aspx) implementation
  * @details
- * The input postfix expression is of type string upto 24 characters (single digit numbers only).
+ * The input postfix expression is of type string upto 49 characters (including space delimiters).
  * Supported operations- '+', '-', '/', '*', '%'
  * @author [Kumar Yash](https://github.com/kumaryash18)
  */
@@ -61,10 +61,19 @@ int8_t evaluate(char post[]) {
 	int8_t it1;
 	int8_t it2;
 	int8_t temp;
+	int8_t number;
     int i;
     for(i = 0; i < strlen(post); i++) {
-		if(isdigit(post[i])) {
-			push(post[i]-'0');
+		if(post[i] == ' ') {
+			continue;			// ignore delimiter
+		}
+		else if(isdigit(post[i])) {
+			number = 0;
+			do {
+				number = number * 10 + (post[i]-'0');
+				i++;
+			} while(i < strlen(post) && isdigit(post[i]));
+			push(number);
 		}
 		else {
 			it2 = pop();
@@ -95,14 +104,16 @@ int8_t evaluate(char post[]) {
  */
 static void test() {
     /* check sample test case
-	   input: "4572+-*"
-	   expected output: -16
+	   input: "2 10 + 9 6 - /"
+	   expected output: 4
 	 */
-	assert(evaluate("4572+-*") == -16); 			/// this ensures that the algorithm works as expected
-	/* input: "42+351-*+"
+	char temp1[50] = "2 10 + 9 6 - /";
+	assert(evaluate(temp1) == 4); 			/// this ensures that the algorithm works as expected
+	/* input: "4 2 + 3 5 1 - * +"
 	   expected output: 18
 	 */
-	assert(evaluate("42+351-*+") == 18); 			/// this ensures that the algorithm works as expected
+	char temp2[50] = "4 2 + 3 5 1 - * +";
+	assert(evaluate(temp2) == 18); 			/// this ensures that the algorithm works as expected
 	printf("All tests have successfully passed!\n");
 }
 
@@ -113,9 +124,9 @@ static void test() {
 int main() {
 	st.top = -1;			/// initialize
 	test();				/// run self-test implementations
-	char post[25];			///< to store input postfix expression
+	char post[50];			///< to store input postfix expression
 	printf("Enter postfix: ");
-	scanf("%s", post);
+	gets(post);
 	printf("Evaluated answer: %d", evaluate(post));
 	return 0;
 }

From 7aa212c260908d20f2ac4de99f12582a4d93bf75 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Sat, 23 Oct 2021 18:10:19 +0530
Subject: [PATCH 18/20] fix: CodeQL

---
 misc/postfix_evaluation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
index faa7993c78..2e0695594b 100644
--- a/misc/postfix_evaluation.c
+++ b/misc/postfix_evaluation.c
@@ -126,7 +126,7 @@ int main() {
 	test();				/// run self-test implementations
 	char post[50];			///< to store input postfix expression
 	printf("Enter postfix: ");
-	gets(post);
+	scanf("%[^\n]%*c", post);
 	printf("Evaluated answer: %d", evaluate(post));
 	return 0;
 }

From cb88c165bbd7a34c828221c918c280f2558e3fd0 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Mon, 25 Oct 2021 17:46:28 +0530
Subject: [PATCH 19/20] docs: documentation changes

---
 misc/postfix_evaluation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
index 2e0695594b..70b0dcb904 100644
--- a/misc/postfix_evaluation.c
+++ b/misc/postfix_evaluation.c
@@ -124,7 +124,7 @@ static void test() {
 int main() {
 	st.top = -1;			/// initialize
 	test();				/// run self-test implementations
-	char post[50];			///< to store input postfix expression
+	char post[50];			/// to store input postfix expression
 	printf("Enter postfix: ");
 	scanf("%[^\n]%*c", post);
 	printf("Evaluated answer: %d", evaluate(post));

From bc0b52b8fc43c2385a65cb67a08566d332aedaa8 Mon Sep 17 00:00:00 2001
From: kumaryash18 <kumaryash1808@gmail.com>
Date: Mon, 25 Oct 2021 21:40:03 +0530
Subject: [PATCH 20/20] remove unnecessary code

---
 misc/postfix_evaluation.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/misc/postfix_evaluation.c b/misc/postfix_evaluation.c
index 70b0dcb904..ca8e97c37f 100644
--- a/misc/postfix_evaluation.c
+++ b/misc/postfix_evaluation.c
@@ -124,9 +124,5 @@ static void test() {
 int main() {
 	st.top = -1;			/// initialize
 	test();				/// run self-test implementations
-	char post[50];			/// to store input postfix expression
-	printf("Enter postfix: ");
-	scanf("%[^\n]%*c", post);
-	printf("Evaluated answer: %d", evaluate(post));
 	return 0;
 }