numbers, clear and back button func add

Author: lyadhcoder

lib/main.dart

@@ -1,10 +1,10 @@
 import 'package:flutter/material.dart';
 
 void main(){
-  runApp(calculator());
+  runApp(Calculator());
 }
 
-class calculator extends StatelessWidget {
+class Calculator extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
 
@@ -23,7 +23,42 @@ class SimpleCalculator extends StatefulWidget {
 
 class _SimpleCalculatorState extends State<SimpleCalculator> {
 
-  Widget BuildButton(String buttonText, double buttonHeight, Color buttonColor){
+  String equation = "0";
+  String result = "0";
+  String expression = "";
+  double equationFontSize = 38.0;
+  double resultFontSize = 48.0;
+
+  buttonPressed(String buttonText){
+    setState(() {
+      if(buttonText == "C"){
+        equation = "0";
+        result = "0";
+        equationFontSize = 38.0;
+        resultFontSize = 48.0;
+      }else if(buttonText == "⌫"){
+        equationFontSize = 48.0;
+        resultFontSize = 38.0;
+        equation = equation.substring(0, equation.length -1);
+        if (equation == ""){
+          equation = "0";
+        }
+      }else if(buttonText == "="){
+        equationFontSize = 38.0;
+        resultFontSize = 48.0;
+      }else{
+        equationFontSize = 48.0;
+        resultFontSize = 38.0;
+        if(equation == "0"){
+          equation = buttonText;
+        }else{
+          equation = equation + buttonText;
+        }
+      }
+    });
+  }
+
+  Widget buildButton(String buttonText, double buttonHeight, Color buttonColor){
     return Container(
       height: MediaQuery.of(context).size.height * 0.1 * buttonHeight,
       color: buttonColor,
@@ -37,7 +72,7 @@ class _SimpleCalculatorState extends State<SimpleCalculator> {
             )
         ),
         padding: EdgeInsets.all(16.0),
-        onPressed: null,
+        onPressed: () => buttonPressed(buttonText),
         child: Text(
           buttonText,
           style: TextStyle(
@@ -59,12 +94,12 @@ class _SimpleCalculatorState extends State<SimpleCalculator> {
           Container(
             alignment: Alignment.centerRight,
             padding: EdgeInsets.fromLTRB(10, 20, 20, 0),
-            child: Text("0", style: TextStyle(fontSize: 38.0),),
+            child: Text(equation, style: TextStyle(fontSize: equationFontSize),),
           ),
           Container(
             alignment: Alignment.centerRight,
             padding: EdgeInsets.fromLTRB(10, 30, 20, 0),
-            child: Text("0", style: TextStyle(fontSize: 48.0),),
+            child: Text(result, style: TextStyle(fontSize: resultFontSize),),
           ),
           Expanded(
             child: Divider(),
@@ -78,12 +113,69 @@ class _SimpleCalculatorState extends State<SimpleCalculator> {
                   children: [
                     TableRow(
                       children: [
-                        BuildButton("C", 1, Colors.redAccent),
+                        buildButton("C", 1, Colors.redAccent),
+                        buildButton("⌫", 1, Colors.blue),
+                        buildButton("÷", 1, Colors.blue),
                       ]
-                    )
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton("7", 1, Colors.black45),
+                          buildButton("8", 1, Colors.black45),
+                          buildButton("9", 1, Colors.black45),
+                        ]
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton("4", 1, Colors.black45),
+                          buildButton("5", 1, Colors.black45),
+                          buildButton("6", 1, Colors.black45),
+                        ]
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton("1", 1, Colors.black45),
+                          buildButton("2", 1, Colors.black45),
+                          buildButton("3", 1, Colors.black45),
+                        ]
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton(".", 1, Colors.black45),
+                          buildButton("0", 1, Colors.black45),
+                          buildButton("00", 1, Colors.black45),
+                        ]
+                    ),
                   ],
                 )
                 ,
+              ),
+              Container(
+                width: MediaQuery.of(context).size.width * 0.25,
+                child: Table(
+                  children: [
+                    TableRow(
+                        children: [
+                          buildButton("×", 1, Colors.blue),
+                        ]
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton("+", 1, Colors.blue),
+                        ]
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton("-", 1, Colors.blue),
+                        ]
+                    ),
+                    TableRow(
+                        children: [
+                          buildButton("=", 2, Colors.redAccent),
+                        ]
+                    )
+                  ],
+                ),
               )
             ],
           ),