Update strings.f90

- Fixed issue in str_replace where the input str indexing would be greater than the str length.

[skip ci]

Author: eengl

strings.f90

@@ -44,15 +44,17 @@ function str_replace(str,old,new) result(strout)
       character(len=*), intent(in) :: old
       character(len=*), intent(in) :: new
       character(len=:), allocatable :: strout
-      integer :: i,len_old,len_new
+      integer :: i,iend,len_str,len_old,len_new
       logical(kind=1), dimension(len_trim(str)) :: work
       work(:)=.false.
+      len_str=len_trim(str)
       len_old=len_trim(old)
       len_new=len_trim(new)
       strout=""
-      do i=1,len_trim(str)
+      do i=1,len_str
          if(work(i))cycle
-         if(str(i:i+(len_old-1)).eq.old)then
+         iend=min(len_str,i+(len_old-1))
+         if(str(i:iend).eq.old)then
             strout=strout//new
             work(i:i+(len_old-1))=.true.
          else
@@ -310,4 +312,4 @@ function str_swapcase(str) result(strout)
       end do
    end function str_swapcase
 
-end module strings
+end module strings