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Commit 1fe2171

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strings: join, to_c_char (#936)
2 parents bec8574 + 1f24d54 commit 1fe2171

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8 files changed

+309
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lines changed

‎doc/specs/stdlib_strings.md‎

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@@ -459,6 +459,43 @@ The result is of the same type as `string`.
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{!example/strings/example_zfill.f90!}
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```
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<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
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### `join`
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#### Description
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Joins an array of strings into a single string. This function concatenates the strings from the input array,
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inserting a separator between each string (default: space). A user-defined separator may be provided, The resulting string is returned.
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#### Syntax
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`joined = ` [[stdlib_strings(module):join(interface)]] ` (strings, separator)`
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#### Status
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Experimental
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#### Class
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Pure function
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#### Argument
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- `strings`: Array of strings (either `type(string_type)` or `character(len=*)`).
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This argument is `intent(in)`. It is an array of strings that will be concatenated together.
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- `separator`: `character(len=*)` scalar (optional).
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This argument is `intent(in)`. It specifies the separator to be used between the strings. If not provided, the default separator (a space) is used.
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#### Result value
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The result is of the same type as the elements of `strings` (`type(string_type)` or `character(len=:), allocatable`).
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#### Example
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```fortran
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{!example/strings/example_join.f90!}
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```
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<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
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### `to_string`
@@ -498,3 +535,38 @@ The result is an `allocatable` length `character` scalar with up to `128` cached
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```fortran
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{!example/strings/example_to_string.f90!}
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```
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<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
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### `to_c_char`
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#### Description
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Convert a Fortran `character` string or a `type(string_type)` variable to a C character array.
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This function converts a Fortran string into a C-style array of characters, ensuring proper null-termination for use in C functions or libraries.
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#### Syntax
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`cstr = ` [[stdlib_strings(module):to_c_char(function)]] ` (value)`
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#### Status
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Experimental
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#### Class
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Pure function.
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#### Argument
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- `value`: Shall be a `character(len=*)` string or a `type(string_type)` variable. It is an `intent(in)` argument.
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This Fortran variable will be converted to a C character array.
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#### Result value
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The result is a `character(kind=c_char)` array with a dimension of `len(value) + 1` to accommodate the null terminator.
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#### Example
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```fortran
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{!example/strings/example_to_c_char.f90!}
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```

‎example/strings/CMakeLists.txt‎

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Original file line numberDiff line numberDiff line change
@@ -2,13 +2,15 @@ ADD_EXAMPLE(chomp)
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ADD_EXAMPLE(count)
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ADD_EXAMPLE(ends_with)
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ADD_EXAMPLE(find)
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ADD_EXAMPLE(join)
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ADD_EXAMPLE(padl)
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ADD_EXAMPLE(padr)
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ADD_EXAMPLE(replace_all)
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ADD_EXAMPLE(slice)
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ADD_EXAMPLE(starts_with)
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ADD_EXAMPLE(strip)
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ADD_EXAMPLE(to_string)
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ADD_EXAMPLE(to_c_char)
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ADD_EXAMPLE(zfill)
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ADD_EXAMPLE(string_to_number)
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ADD_EXAMPLE(stream_of_strings_to_numbers)
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ADD_EXAMPLE(stream_of_strings_to_numbers)

‎example/strings/example_join.f90‎

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@@ -0,0 +1,20 @@
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program example_join
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use stdlib_strings, only: join
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implicit none
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character(len=:), allocatable :: line
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character(*), parameter :: words(3) = [character(7) :: "Hello", "World", "Fortran"]
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! Default separator (space)
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line = join(words)
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print *, "'" // line // "'" !! 'Hello World Fortran'
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! Custom separator
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line = join(words, "_")
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print *, "'" // line // "'" !! 'Hello_World_Fortran'
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! Custom 2-character separator
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line = join(words, ", ")
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print *, "'" // line // "'" !! 'Hello, World, Fortran'
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end program example_join
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@@ -0,0 +1,20 @@
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program example_to_c_char
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use stdlib_strings, only: to_c_char
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use stdlib_string_type, only: string_type
4+
use stdlib_kinds, only: c_char
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implicit none
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character(kind=c_char), allocatable :: cstr(:),cstr2(:)
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character(*), parameter :: hello = "Hello, World!"
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! Convert character array
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cstr = to_c_char(hello)
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! Convert string type
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cstr2 = to_c_char(string_type(hello))
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if (size(cstr)/=size(cstr2) .or. .not.all(cstr==cstr2)) then
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error stop 'String conversion error'
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end if
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end program example_to_c_char

‎src/stdlib_kinds.fypp‎

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@@ -4,10 +4,10 @@
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!> The specification of this module is available [here](../page/specs/stdlib_kinds.html).
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module stdlib_kinds
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use iso_fortran_env, only: int8, int16, int32, int64
7-
use iso_c_binding, only: c_bool
7+
use iso_c_binding, only: c_bool, c_char
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implicit none
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private
10-
public :: sp, dp, xdp, qp, int8, int16, int32, int64, lk, c_bool
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public :: sp, dp, xdp, qp, int8, int16, int32, int64, lk, c_bool, c_char
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!> Single precision real numbers
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integer, parameter :: sp = selected_real_kind(6)

‎src/stdlib_strings.fypp‎

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Original file line numberDiff line numberDiff line change
@@ -5,16 +5,18 @@
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!> The specification of this module is available [here](../page/specs/stdlib_strings.html).
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module stdlib_strings
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use stdlib_ascii, only: whitespace
8-
use stdlib_string_type, only: string_type, char, verify, repeat, len
8+
use stdlib_string_type, only: string_type, char, verify, repeat, len, len_trim, move
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use stdlib_optval, only: optval
10-
use stdlib_kinds, only: sp, dp, xdp, qp, int8, int16, int32, int64, lk, c_bool
10+
use stdlib_kinds, only: sp, dp, xdp, qp, int8, int16, int32, int64, lk, c_bool, c_char
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use iso_c_binding, only: c_null_char
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implicit none
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private
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public :: to_string
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public :: to_c_char
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public :: strip, chomp
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public :: starts_with, ends_with
17-
public :: slice, find, replace_all, padl, padr, count, zfill
19+
public :: slice, find, replace_all, padl, padr, count, zfill, join
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!> Version: experimental
2022
!>
@@ -43,6 +45,15 @@ module stdlib_strings
4345
#:endfor
4446
end interface to_string
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!> Version: experimental
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!>
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!> Format or transfer other types as a string.
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!> ([Specification](../page/specs/stdlib_strings.html#to_c_char))
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interface to_c_char
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module procedure to_c_char_from_char
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module procedure to_c_char_from_string
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end interface to_c_char
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!> Remove leading and trailing whitespace characters.
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!>
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!> Version: experimental
@@ -164,6 +175,17 @@ module stdlib_strings
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module procedure :: zfill_char
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end interface zfill
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!> Version: experimental
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!>
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!> Joins an array of strings into a single string.
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!> The chunks are separated with a space, or an optional user-defined separator.
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!> [Specifications](../page/specs/stdlib_strings.html#join)
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interface join
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module procedure :: join_string
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module procedure :: join_char
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end interface join
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contains
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@@ -943,5 +965,97 @@ contains
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end function zfill_char
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!> Convert a Fortran character string to a C character array
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!>
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!> Version: experimental
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pure function to_c_char_from_char(value) result(cstr)
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character(len=*), intent(in) :: value
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character(kind=c_char) :: cstr(len(value)+1)
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integer :: i,lv
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lv = len(value)
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do concurrent (i=1:lv)
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cstr(i) = value(i:i)
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end do
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cstr(lv+1) = c_null_char
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end function to_c_char_from_char
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!> Convert a Fortran string type to a C character array
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!>
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!> Version: experimental
985+
pure function to_c_char_from_string(value) result(cstr)
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type(string_type), intent(in) :: value
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character(kind=c_char) :: cstr(len(value)+1)
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integer :: i,lv
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lv = len(value)
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do concurrent (i=1:lv)
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cstr(i) = char(value,pos=i)
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end do
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cstr(lv+1) = c_null_char
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end function to_c_char_from_string
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!> Joins a list of strings with a separator (default: space).
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!> Returns a new string
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pure type(string_type) function join_string(strings, separator)
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type(string_type), intent(in) :: strings(:)
1000+
character(len=*), intent(in), optional :: separator
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integer :: ltot, i, lt, pos
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character(len=:), allocatable :: sep,joined
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! Determine separator: use user-provided separator or default space
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if (present(separator)) then
1005+
sep = separator
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else
1007+
sep = ' '
1008+
end if
1009+
! Calculate the total length required, including separators
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ltot = sum(len_trim(strings)) + (size(strings) - 1) * len(sep)
1011+
allocate(character(len=ltot) :: joined)
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! Concatenate strings with separator
1014+
pos = 0
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do i = 1, size(strings)
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lt = len_trim(strings(i))
1017+
joined(pos+1:pos+lt) = char(strings(i),1,lt)
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pos = pos + lt
1019+
if (i < size(strings)) then
1020+
joined(pos+1:pos+len(sep)) = sep
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pos = pos + len(sep)
1022+
end if
1023+
end do
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1025+
call move(from=joined,to=join_string)
1026+
1027+
end function join_string
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!> Joins a list of strings with a separator (default: space).
1030+
!> Returns a new string
1031+
pure function join_char(strings, separator) result(joined)
1032+
character(*), intent(in) :: strings(:)
1033+
character(len=*), intent(in), optional :: separator
1034+
character(len=:), allocatable :: joined
1035+
integer :: ltot, i, lt, pos
1036+
character(len=:), allocatable :: sep
1037+
! Determine separator: use user-provided separator or default space
1038+
if (present(separator)) then
1039+
sep = separator
1040+
else
1041+
sep = ' '
1042+
end if
1043+
! Calculate the total length required, including separators
1044+
ltot = sum(len_trim(strings)) + (size(strings) - 1) * len(sep)
1045+
allocate(character(len=ltot) :: joined)
1046+
1047+
joined = repeat(' ',ltot)
1048+
! Concatenate strings with separator
1049+
pos = 0
1050+
do i = 1, size(strings)
1051+
lt = len_trim(strings(i))
1052+
joined(pos+1:pos+lt) = strings(i)(1:lt)
1053+
pos = pos + lt
1054+
if (i < size(strings)) then
1055+
joined(pos+1:pos+len(sep)) = sep
1056+
pos = pos + len(sep)
1057+
end if
1058+
end do
1059+
end function join_char
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9471061
end module stdlib_strings

‎test/string/test_string_match.f90‎

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Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@
22
module test_string_match
33
use testdrive, only : new_unittest, unittest_type, error_type, check
44
use stdlib_ascii, only : reverse
5-
use stdlib_strings, only : starts_with, ends_with
5+
use stdlib_strings, only : starts_with, ends_with, join
66
use stdlib_string_type, only : string_type
77
implicit none
88

@@ -16,7 +16,8 @@ subroutine collect_string_match(testsuite)
1616

1717
testsuite = [ &
1818
new_unittest("starts_with", test_starts_with), &
19-
new_unittest("ends_with", test_ends_with) &
19+
new_unittest("ends_with", test_ends_with), &
20+
new_unittest("join", test_join) &
2021
]
2122
end subroutine collect_string_match
2223

@@ -77,6 +78,32 @@ subroutine check_ends_with(error, string, substring)
7778
call check(error, ends_with(string_type(string), string_type(substring)) .eqv. match, message)
7879
end subroutine check_ends_with
7980

81+
subroutine test_join(error)
82+
type(error_type), allocatable, intent(out) :: error
83+
character(len=5) :: test_strings(3)
84+
85+
test_strings = [character(5) :: "one", "two", "three"]
86+
call check_join(error, test_strings, " ", "one two three")
87+
if (allocated(error)) return
88+
call check_join(error, test_strings, ",", "one,two,three")
89+
if (allocated(error)) return
90+
call check_join(error, test_strings, "-", "one-two-three")
91+
end subroutine test_join
92+
93+
subroutine check_join(error, strings, separator, expected)
94+
type(error_type), allocatable, intent(out) :: error
95+
character(len=*), intent(in) :: strings(:)
96+
character(len=*), intent(in) :: separator
97+
character(len=*), intent(in) :: expected
98+
character(len=:), allocatable :: joined
99+
character(len=:), allocatable :: message
100+
101+
joined = join(strings, separator)
102+
message = "'join' error: Expected '" // expected // "' but got '" // joined // "'"
103+
call check(error, joined == expected, message)
104+
105+
end subroutine check_join
106+
80107
subroutine test_ends_with(error)
81108
type(error_type), allocatable, intent(out) :: error
82109
call check_ends_with(error, "pattern", "pat")

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