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Manual Reference Pages  - encode_base64 (3m_strings)

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NAME

encode_base64-(3f) - [M_strings:ENCODE] encode data using base64 encoding as defined in RFC-4648 (LICENSE:MIT)

CONTENTS

Synopsis
Description
Options
Output
Example
See Also

SYNOPSIS

function encode_base64(text,width) result(out)

     character(len=1),intent(in) :: text(*)
     integer,intent(in),optional :: width
     character(len=1),allocatable :: out(:)

DESCRIPTION

The data is encoded as described for the base64-alphabet-encoding in RFC 4648.

OPTIONS

TEXT	Data to encode
WIDTH	wrap encoded lines after specified number of characters (default 76). Use 0 to disable line wrapping

OUTPUT

OUT	array of encoded characters representing input text

EXAMPLE

Sample program:

   program demo_encode_base64
   use,intrinsic :: iso_fortran_env, only : int8, int16, int32, int64
   use M_strings, only : switch, encode_base64, decode_base64
   implicit none
   integer                      :: i
   character(len=1),parameter   :: nl=new_line(’a’)
   character(len=1),allocatable :: textin(:), textout(:)
   character(len=*),parameter   :: data(*)=[ &
   ’This is some sample data          ’,  &
   ’To encode. Should make it long    ’,  &
   ’enough to generate multiple lines ’,  &
   ’of output so can check line wrap  ’,  &
   ’functionality as well.            ’   &
   ]
   ! make a file-like byte stream by trimming lines and adding newlines
      textin=[(switch(trim(data(i))),new_line(’a’),i=1,size(data))]
      write(*,’(*(a))’)’input:’,nl,textin
   !
      textout=encode_base64(textin,width=50)
      write(*,’(*(a))’)’result:’,nl, textout
   !
      write(*,’(*(a))’)’decode result:’,nl, decode_base64(textout)
   !
   ! one way to encode non-byte data
      call other()
   contains
   subroutine other()
   real                         :: arr1(100)
   character(len=1),allocatable :: in(:)
   character(len=1),allocatable :: out(:)
   real,allocatable             :: arr2(:)
      ! fill a real array with some values
      arr1=[(sqrt(real(i)),i=1,size(arr1))]
      ! use TRANSFER() to convert data to bytes
      in=transfer(source=arr1,mold=[’+’])
      ! encode the bytes
      out=encode_base64(in)
      ! decode the bytes
      out=decode_base64(out)
      ! store the bytes back into arr1
      arr2=transfer(source=out,mold=[0.0])
      write(*,’(*(g0,1x))’) ’are arr1 and arr2 the same?’,all(arr1.eq.arr2)
   end subroutine other
   end program demo_encode_base64

Results:

 > input:
 > This is some sample data
 > To encode. Should make it long
 > enough to generate multiple lines
 > of output so can check line wrap
 > functionality as well.
 >
 > result:
 > VGhpcyBpcyBzb21lIHNhbXBsZSBkYXRhClRvIGVuY29kZS4gU2
 > hvdWxkIG1ha2UgaXQgbG9uZwplbm91Z2ggdG8gZ2VuZXJhdGUg
 > bXVsdGlwbGUgbGluZXMKb2Ygb3V0cHV0IHNvIGNhbiBjaGVjay
 > BsaW5lIHdyYXAKZnVuY3Rpb25hbGl0eSBhcyB3ZWxsLgo=
 >
 > decode result:
 > This is some sample data
 > To encode. Should make it long
 > enough to generate multiple lines
 > of output so can check line wrap
 > functionality as well.
 >
 > are arr1 and arr2 the same? T

SEE ALSO

decode_base64(3), base64(1), uuencode(1), uudecode(1)

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