Added str_test function

Added new function, str_test, to test the if a substring is in a string (.true.), otherwise (.false.).

strings.f90 - Added str_test -- basically a wrapper for str_count and returning a .true./.false. based on returned count of substring.

Updated docs and tests.

Author: eengl

README.md

@@ -19,8 +19,9 @@ The function names are prefixed with ``str_``.  The following is a list of avail
 * **str_zfill** - Pad a string with zeroes ("0") to specified width. If width is <= input string width, then the original string is returned.
 * **str_center** - Center a string to a specified width.  The default character to fill in the centered string is a blank character.
 * **str_reverse** - Reverse a string.
+* **str_test** - Return .true. is a substring is found in a string, .false. otherwise.
 
-All functions return a deferred-length, allocatable character scalar (``character(len=:), allocatable``) with the exception of **``str_count``** which returns an integer.
+All functions return a deferred-length, allocatable character scalar (``character(len=:), allocatable``) with the exception of **``str_count``** which returns an integer and **``str_test``** which returns a logical.
 
 ## Requirements
 

strings.f90

@@ -249,4 +249,23 @@ function str_reverse(str) result(strout)
       end do
    end function str_reverse
 
+   ! -------------------------------------------------------------------------------------
+   ! Function: str_test
+   !> @brief Return .true. if substr is in str, .false. otherwise
+   !> @param[in] str - string to work on
+   !> @param[in] substr - string to search for in str
+   !> @return .true. or .false.
+   ! -------------------------------------------------------------------------------------
+   function str_test(str,substr) result(strtest)
+      implicit none
+      character(len=*), intent(in) :: str
+      character(len=*), intent(in) :: substr
+      logical :: strtest
+      if(str_count(str,substr).eq.0)then
+         strtest=.false.
+      elseif(str_count(str,substr).gt.0)then
+         strtest=.true.
+      endif
+   end function str_test
+
 end module strings

test/test.f90

@@ -4,6 +4,7 @@ program test
 
    character(len=:), allocatable :: c1,c2
    integer :: i1
+   logical :: l1
 
    c1="My name is Tony Stark.  Tony Stark is Iron Man."
    !print *,"MYSTRING = ",c1
@@ -60,4 +61,12 @@ program test
    c2=str_reverse(c1)
    !print *,"STR_REVERSE = ",":",c2,":"
 
+   c1="Ironman,Thor,Thanos,Black Panther,Winter Soldier"
+   l1=str_test(c1,"Thor") ! TRUE
+   !print *,l1
+   if(.not.l1)call exit(1)
+   l1=str_test(c1,"Vision") ! FALSE
+   !print *,l1
+   if(l1)call exit(1)
+
 end program test