file handling between different functions.

[EDIT: 20110614 13:44 CDT - reformat - WDR]

there are three functions A, B, C

A - main function creates a file with the prompted filename
  fid = fopen('filename');
  call function B
  close all files with fclose('all');
  
B - process some data and printf out to file speicified with fid
  fprintf(fid, '%e, ...\n', var);
  call function C
  
C - process some data and printf out to file speicified with fid
  fprintf(fid, '%e, ...\n', var);
  end

fid is declared in all three functions A, B, C as global by

function A
global fid;
fid = fopen('filename');
..
call function B;
..
fclose('all');

function B
global fid;

process data
fprintf(fid, '%e, ...\n', var);
..
call function C
...

function C
global fid;

process data
fprintf(fid, '%e, ...\n', var);
..

but it does not work at all. is there anyway to make the file be accessaible by the all three functions?

Answer 1

[Walter Roberson]

That looks like it should work. What value do you see for fid in function B after the "global" line has been executed?

Answer 2

[Fangjun Jiang]

It works for me. Try it yourself.

function a=FunA
    global fid;
    a=0;
    fid=fopen('test.txt','wt');
    fprintf(fid,'function a\n');
    FunB;
    fclose('all');
end

function b=FunB
    global fid;
    b=0;
    fprintf(fid,'function b\n');
    FunC;
end

function c=FunC
    c=0;
    global fid;
    fprintf(fid,'function c\n');
end

Answer 3

[Chirag Gupta]

Just pass the fid from function to function.

function A(filename)

fid = fopen(filename,'w');

% call function B
B(fid,other params);
%...

function B(fid,other_params)
% use passed fid to fprintf
% call C and pass fid
C(fid,other_params
%...

function C(fid,...)
%...

Is there any reason why you want the fid as global?