How can I export variable to a text file in mex file ?

Dear Friends,

I am working MATLAB Version 7.6.0.324 (R2008a) with Microsoft Visual C++ 2010 compiler.

I want to export my variable to a text file, here some lines of my c file:

/* amsubread6.c - MATLAB mex file for reading AMSU-B data

/* Usage: amsub = amsubread6(amsubfile)

#include "mex.h"

#include <stdio.h>

#include <stdlib.h>

#include <fcntl.h>

#define NUM_CHANNELS 5

.
.
.

void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{

mxArray *tb_mat, *lat_mat, *lon_mat;

double *tb[NUM_CHANNELS], *lat, *lon; 

int dims[2] = {NUM_CHANNELS, 1};

.
.
.

tb_mat = mxCreateCellArray(2, dims);

mxSetCell(tb_mat, channel, mxCreateDoubleMatrix(num_spots,num_scans, mxREAL));

tb[channel] = mxGetPr(mxGetCell(tb_mat, channel));

mxSetFieldByNumber(plhs[0], 0, 0, tb_mat);

lat_mat = mxCreateDoubleMatrix(num_spots,num_scans, mxREAL);

      lat = mxGetPr(lat_mat);

mxSetFieldByNumber(plhs[0], 0, 1, lat_mat);

lon_mat = mxCreateDoubleMatrix(num_spots,num_scans, mxREAL);

      lon = mxGetPr(lon_mat);

mxSetFieldByNumber(plhs[0], 0, 2, lon_mat);

.
.
.

How can I export tb[], lat, lon to a text file like this format :

lat  lon  tb[1] tb[2] tb[3] tb[4] tb[5]

Thanks for your help

[James Tursa]

Do you mean lat[0] and lon[0]?

[hadi]

Hi James,

My C files has several outputs : ans =

       tb: {5x1 cell}
      lat: [90x2416 double]
      lon: [90x2416 double]
     solz: [90x2416 double]
     satz: [90x2416 double]
       az: [90x2416 double]
      ssa: [90x2416 double]
     roll: [1x2416 double]
    pitch: [1x2416 double]
      yaw: [1x2416 double]
     time: [1x2416 double]
    sdate: [1x2416 double]
      dir: [1x2416 double]

I want to export these outputs to a text file.

Answer 1

[José-Luis]

Hello!

Have a look here http://www.cplusplus.com/doc/tutorial/files/

#include <iostream>
#include <fstream>
using namespace std;

ofstream myfile;
myfile.open ("my_file.txt");
//A loop will probably required here
myfile << "lat" << " " << "lon" << " "  << val1 << " " << [...] << endl;
myfile.close();

Cheers!

[hadi]

Hi Jose-Luis,

when I used

#include <fstream>

some errors found like these lines:

C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\cmath(19) : error C2061: syntax error : identifier 'acosf'

C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\cmath(19) : error C2059: syntax error : ';'

[Walter Roberson]

What file extension did you save the code as? <fstream> and other aspects of the code shown are for C++ and would not compile if saved to a .c file. Your original code is C code.

[hadi]

yes, you right Walter, but I tested for Jose-Luis to show him the errors !

[José-Luis]

True, the my answer was C++. If you want plain C, then you can use fopen and fprintf.

http://pubs.opengroup.org/onlinepubs/009695399/functions/printf.html

[hadi]

I used these codes :

#include <stdio.h>
char Tfilename;
int Tfile;
Tfilename = "log.txt";
Tfile = open(Tfilename, O_WRONLY);

if i use

mexPrintf(Tfile,"%f ", ...

Matlab will be crashed

for printf, fprintf or sprintf

error is :

amsubread6.obj : error LNK2019: unresolved external symbol _fPrintf referenced in function _mexFunction

amsubread6.mexw32 : fatal error LNK1120: 1 unresolved externals

Can you tell me, what is wrong ?