diff --git a/doc/specs/stdlib_ascii.md b/doc/specs/stdlib_ascii.md
index 5a6653337..fbc1b4982 100644
--- a/doc/specs/stdlib_ascii.md
+++ b/doc/specs/stdlib_ascii.md
@@ -169,3 +169,39 @@ program demo_reverse
print'(a)', reverse("Hello, World!") ! returns "!dlroW ,olleH"
end program demo_reverse
```
+
+### `sort`
+
+#### Status
+
+Experimental
+
+#### Description
+
+Sorts all the characters in the input character type according to their ascii values.
+
+#### Syntax
+
+`res = [[stdlib_ascii(module):sort(function)]] (string)`
+
+#### Class
+
+Pure function.
+
+#### Argument
+
+`string`: shall be an intrinsic character type. It is an `intent(in)` argument.
+
+#### Result value
+
+The result is an intrinsic character type of the same length as `string`.
+
+#### Example
+
+```fortran
+program demo_sort
+ use stdlib_ascii, only : sort
+ implicit none
+ print'(a)', sort("Sort This String") ! returns " SSTghiinorrstt"
+end program demo_sort
+```
\ No newline at end of file
diff --git a/doc/specs/stdlib_string_type.md b/doc/specs/stdlib_string_type.md
index 63c38ccf4..b5bf9a18e 100644
--- a/doc/specs/stdlib_string_type.md
+++ b/doc/specs/stdlib_string_type.md
@@ -1221,6 +1221,50 @@ program demo
end program demo
```
+<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
+### Sort function
+
+#### Description
+
+Returns a new string_type instance which holds the sorted version of the character sequence hold by the input string.
+
+#### Syntax
+
+`sorted_string = [[stdlib_string_type(module): sort(interface)]] (string)`
+
+#### Status
+
+Experimental
+
+#### Class
+
+Elemental function.
+
+#### Argument
+
+`string`: Instance of `string_type`. This argument is `intent(in)`.
+
+#### Result Value
+
+The Result is a scalar `string_type` value.
+
+#### Example
+
+```fortran
+program demo
+ use stdlib_string_type
+ implicit none
+ type(string_type) :: string, sorted_string
+
+ string = "Sort This String"
+ ! string <-- "Sort This String"
+
+ sorted_string = sort(string)
+ ! string <-- "Sort This String"
+ ! sorted_string <-- " SSTghiinorrstt"
+end program demo
+```
+
<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
### Comparison operator greater
diff --git a/src/stdlib_ascii.f90 b/src/stdlib_ascii.f90
index e446f29e2..c7f5cfccc 100644
--- a/src/stdlib_ascii.f90
+++ b/src/stdlib_ascii.f90
@@ -16,7 +16,7 @@ module stdlib_ascii
public :: is_lower, is_upper
! Character conversion functions
- public :: to_lower, to_upper, to_title, reverse
+ public :: to_lower, to_upper, to_title, reverse, sort
! All control characters in the ASCII table (see www.asciitable.com).
character(len=1), public, parameter :: NUL = achar(int(z'00')) !! Null
@@ -92,6 +92,13 @@ module stdlib_ascii
interface reverse
module procedure :: reverse
end interface reverse
+
+ !> Returns a new character sequence which sorted version of
+ !> the input charater sequence
+ !> This method is pure and returns a character sequence
+ interface sort
+ module procedure :: sort
+ end interface sort
contains
@@ -312,4 +319,30 @@ pure function reverse(string) result(reverse_string)
end function reverse
+
+ !> Sort the character order in the input character variable
+ !> Version: experimental
+ pure function sort(string) result(sorted_string)
+ character(len=*), intent(in) :: string
+ character(len=len(string)) :: sorted_string
+ integer, dimension(128) :: count
+ integer :: i,j
+ !implementation
+ do i = 1, 128
+ count(i) = 0
+ end do
+
+ do i = 1, len(string)
+ count(iachar(string(i:i))) = count(iachar(string(i:i))) + 1
+ end do
+ j = 1
+ do i = 1, 128
+ do while (count(i)>0)
+ sorted_string(j:j) = achar(i)
+ j = j+1
+ count(i) = count(i) - 1;
+ end do
+ end do
+ end function sort
+
end module stdlib_ascii
diff --git a/src/stdlib_string_type.f90 b/src/stdlib_string_type.f90
index 2b46a5de9..f2f28fe79 100644
--- a/src/stdlib_string_type.f90
+++ b/src/stdlib_string_type.f90
@@ -13,7 +13,7 @@
!> The specification of this module is available [here](../page/specs/stdlib_string_type.html).
module stdlib_string_type
use stdlib_ascii, only: to_lower_ => to_lower, to_upper_ => to_upper, &
- to_title_ => to_title, reverse_ => reverse
+ to_title_ => to_title, reverse_ => reverse, sort_ => sort
implicit none
private
@@ -21,7 +21,7 @@ module stdlib_string_type
public :: string_type
public :: len, len_trim, trim, index, scan, verify, repeat, adjustr, adjustl
public :: lgt, lge, llt, lle, char, ichar, iachar
- public :: to_lower, to_upper, to_title, reverse
+ public :: to_lower, to_upper, to_title, reverse, sort
public :: assignment(=)
public :: operator(>), operator(>=), operator(<), operator(<=)
public :: operator(==), operator(/=), operator(//)
@@ -125,6 +125,14 @@ module stdlib_string_type
module procedure :: reverse_string
end interface reverse
+ !> Sorts the character sequence hold by the input string
+ !>
+ !> This method is Elemental and returns a new string_type instance which holds this
+ !> sorted character sequence
+ interface sort
+ module procedure :: sort_string
+ end interface sort
+
!> Return the character sequence represented by the string.
!>
!> This method is elemental and returns a scalar character value.
@@ -522,6 +530,14 @@ elemental function reverse_string(string) result(reversed_string)
end function reverse_string
+ !> Sorts the character sequence hold by the input string
+ elemental function sort_string(string) result(sorted_string)
+ type(string_type), intent(in) :: string
+ type(string_type) :: sorted_string
+
+ sorted_string%raw = sort_(maybe(string))
+
+ end function sort_string
!> Position of a sequence of character within a character sequence.
!> In this version both character sequences are represented by a string.
diff --git a/src/tests/ascii/test_ascii.f90 b/src/tests/ascii/test_ascii.f90
index cfe4a938c..3623e9dac 100644
--- a/src/tests/ascii/test_ascii.f90
+++ b/src/tests/ascii/test_ascii.f90
@@ -6,7 +6,7 @@ program test_ascii
whitespace, letters, is_alphanum, is_alpha, is_lower, is_upper, &
is_digit, is_octal_digit, is_hex_digit, is_white, is_blank, &
is_control, is_punctuation, is_graphical, is_printable, is_ascii, &
- to_lower, to_upper, to_title, reverse, LF, TAB, NUL, DEL
+ to_lower, to_upper, to_title, reverse, LF, TAB, NUL, DEL, sort
implicit none
@@ -72,6 +72,7 @@ program test_ascii
call test_to_lower_string
call test_to_title_string
call test_reverse_string
+ call test_sort_string
contains
@@ -613,4 +614,18 @@ subroutine test_reverse_string
call check(trim(adjustl(dlc)) == "desrever")
end subroutine test_reverse_string
+ subroutine test_sort_string
+ character(len=:), allocatable :: dlc
+ character(len=32), parameter :: input = "This is to be sorted"
+
+ dlc = sort("This is to be sorted")
+ call check(dlc == " Tbdeehiioorssstt")
+
+ dlc = sort(input)
+ call check(len(dlc) == 32)
+ call check(len_trim(dlc) == 32)
+ call check(trim(dlc) == " Tbdeehiioorssstt")
+ call check(trim(adjustl(dlc)) == "Tbdeehiioorssstt")
+ end subroutine test_sort_string
+
end program test_ascii
diff --git a/src/tests/string/test_string_functions.f90 b/src/tests/string/test_string_functions.f90
index 4a8d516a8..669700a46 100644
--- a/src/tests/string/test_string_functions.f90
+++ b/src/tests/string/test_string_functions.f90
@@ -2,7 +2,7 @@
module test_string_functions
use stdlib_error, only : check
use stdlib_string_type, only : string_type, assignment(=), operator(==), &
- to_lower, to_upper, to_title, reverse
+ to_lower, to_upper, to_title, reverse, sort
implicit none
contains
@@ -43,6 +43,15 @@ subroutine test_reverse_string
end subroutine test_reverse_string
+ subroutine test_sort_string
+ type(string_type) :: test_string, compare_string
+ test_string = "Sort my Life"
+ compare_string = " LSefimorty"
+
+ call check(sort(test_string) == compare_string)
+
+ end subroutine test_sort_string
+
end module test_string_functions
@@ -54,5 +63,6 @@ program tester
call test_to_upper_string
call test_to_title_string
call test_reverse_string
+ call test_sort_string
end program tester