title: fortran write base64 string of binary to file
body: <p>How can I write to a binary file a base64 string representation of data?</p>
  <pre><code>program main
     implicit none
  
     real :: var1, var2, var3, var4
     character(len=:), allocatable :: var
  
     var1 = 1.23
     var2 = 2.35
  
     ! var1, var2 written to file, should output &quot;1.23, 2.35&quot;
     var = 'CAAAAKRwnT9mZhZACAAAAAgAAABSuA5AMzOLQAgAAAA='
  
     open(53, status='scratch', access='stream', action='readwrite', form='unformatted')
  
     write(53) var1, var2 ! write some data
     write(53) var1+1., var2+2. ! write some more data
     write(53) var ! write the base64 string, I want this line to be the same numbers as the first line I wrote
  
     rewind(53) ! reset for reading each line we wrote
     read(53) var3, var4 ! read first line
     print *, var3, var4
     read(53) var3, var4 ! read second line
     print *, var3, var4
     read(53) var3, var4 ! read third line, reads as if this was a string representation
     print *, var3, var4
     close(53)
  end program main
  </code></pre>
  <p>outputs:</p>
  <pre class="lang-bash prettyprint-override"><code>   1.23000002       2.34999990    
     2.23000002       4.34999990    
     12.0784330       4.26526825E+33
  </code></pre>
  <p>I know there is a missing step of converting base64 to a binary form, as the file writes binary data of a string rather than the data it represents, how do I go about converting to binary when writing?</p>