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Programming-Idioms

History of Idiom 63 > diff from v40 to v41

Edit summary for version 41 by tkoenig:
[Fortran] Added missing initialization for k
↷

Version 40

2019-09-29, 15:06:15

Version 41

2019-10-01, 22:19:17

Idiom #63 Replace fragment of a string

Assign to x2 the value of string x with all occurrences of y replaced by z.
Assume occurrences of y are not overlapping.

Idiom #63 Replace fragment of a string

Assign to x2 the value of string x with all occurrences of y replaced by z.
Assume occurrences of y are not overlapping.

Extra Keywords
substring substitute
Extra Keywords
substring substitute
Code 
  character(len=:), allocatable :: x
  character(len=:), allocatable :: x2
  character(len=:), allocatable :: y,z
  integer :: j, k

  do
     j = index(x(k:),y)
     if (j==0) then
        x2 = x2 // x(k:)
        exit
     end if
     if (j>1) then
        x2 = x2 // x(k:j+k-2)
     end if
     x2 = x2 // z
     k = k + j + len(y) - 1
  end do
Code 
  character(len=:), allocatable :: x
  character(len=:), allocatable :: x2
  character(len=:), allocatable :: y,z
  integer :: j, k
  k=1
  do
     j = index(x(k:),y)
     if (j==0) then
        x2 = x2 // x(k:)
        exit
     end if
     if (j>1) then
        x2 = x2 // x(k:j+k-2)
     end if
     x2 = x2 // z
     k = k + j + len(y) - 1
  end do
Comments bubble
This code uses reallocation on assignment for character variables. An alternative implementation might count bytes first, then allocate, then do this.

Note that _// is string concatenation in Fortran.
Comments bubble
This code uses reallocation on assignment for character variables. An alternative implementation might count bytes first, then allocate, then do this.

Note that _// is string concatenation in Fortran.