Manual Reference Pages - switch (3)

NAME

switch(3f) - [M_strings:ARRAY] converts between CHARACTER scalar and array of single characters (LICENSE:PD)

Synopsis
Description
Examples
Author
License

SYNOPSIS


pure function switch(array) result ((string))

    character(len=1),intent(in) :: array(:)
    character(len=SIZE(array))  :: string

     or

pure function switch((string)) result ((array))

    character(len=1),intent(in) :: array(:)
    character(len=SIZE(array))  :: string

DESCRIPTION

SWITCH(3f): generic function that switches CHARACTER (string) to an (array) of single characters or an (array) of single characters to a CHARACTER (string). Useful in passing strings to C. New Fortran features may supersede these routines.

EXAMPLES

Sample program:

   program demo_switch
   use M_strings, only : switch, isalpha, islower, nospace
   character(len=*),parameter :: dashes=’-----------------------------------’
   character(len=*),parameter :: string=’This is a string of letters’
   character(len=1024)        :: line

   ! First, examples of standard Fortran features
   write(*,*)[’A’,’=’,’=’,’=’,’=’,’=’].eq.’=’      ! returns array [F,T,T,T,T,T]
   write(*,*)all([’=’,’=’,’=’,’=’,’=’,’=’].eq.’=’) ! this would return T
   write(*,*)all([’A’,’=’,’=’,’=’,’=’,’=’].eq.’=’) ! this would return F

   ! so to test if the string DASHES is all dashes using SWITCH(3f) is
   if(all(switch(dashes).eq.’-’))then
      write(*,*)’DASHES is all dashes’
   endif

   ! so to test is a string is all letters
   ! isalpha(3f) returns .true. only if character is a letter
   write(*,*) all(isalpha(switch(dashes)))  ! false because dashes are not a letter
   write(*,*) all(isalpha(switch(string)))  ! false because of spaces
   write(*,*) all(isalpha(switch(nospace(string))))  ! true because removed whitespace

   ! to see if a string is all uppercase
   write(*,*) string                           ! show the string
   write(*,’(1x,*("[",a,"]":))’) switch(string)   ! converted to character array
   write(*,’(*(l3))’) islower(switch(string))

   line=nospace(string)                        ! we need a string that is all letters
   write(*,*)’LINE=’,trim(line)
   write(*,*) islower(switch(nospace(string))) ! all true except first character
   write(*,*) all(islower(switch(nospace(string))))      ! should be false
   write(*,*) all(islower(switch(nospace(string(2:)))))  ! should be true

   end program demo_switch

Expected output

   >  F T T T T T
   >  T
   >  F
   >  DASHES is all dashes
   >  F
   >  F
   >  T
   >  This is a string of letters
   >  [T][h][i][s][ ][i][s][ ][a][ ][s][t][r][i][n][g][ ][o][f][ ][l][e][t][t][e][r][s]
   >   F  T  T  T  F  T  T  F  T  F  T  T  T  T  T  T  F  T  T  F  T  T  T  T  T  T  T
   >  LINE=Thisisastringofletters
   >  F T T T T T T T T T T T T T T T T T T T T T
   >  F
   >  T

AUTHOR

John S. Urban

LICENSE

Public Domain

switch (3)

July 05, 2020

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