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.Dd September 12, 2019
.Dt MAT_VARREADNEXT 3
.Os
.Sh NAME
.Nm Mat_VarReadNext
.Nd Reads the information and data for the next variable in a MATLAB MAT file.
.Sh SYNOPSIS
.Fd #include <matio.h>
.Ft matvar_t *
.Fo Mat_VarReadNext
.Fa "mat_t *matfp"
.Fc
.Sh DESCRIPTION
The
.Fn Mat_VarReadNext
function reads the information and data for the next variable stored in the
open MAT file.
.Sh RETURN VALUES
If there is another variable in the MAT file and is read successfully, a
pointer to the MATLAB variable structure is returned.
If there are no more variables, or there was an error reading the variable,
NULL is returned.
.Sh EXAMPLES
This example program opens a MAT file named by the first argument to the
program, and uses
.Fn Mat_VarReadNext
to read each variable in the file.
For each variable read, the
.Fn Mat_VarPrint 3
function is used to display the information and data of the variable.
.Bd -literal
#include <stdlib.h>
#include <stdio.h>
#include "matio.h"

int
main(int argc, char **argv)
{
    mat_t    *matfp;
    matvar_t *matvar;

    matfp = Mat_Open(argv[1], MAT_ACC_RDONLY);
    if ( NULL == matfp ) {
        fprintf(stderr, "Error opening MAT file %s\n", argv[1]);
        return EXIT_FAILURE;
    }

    while ( NULL != (matvar = Mat_VarReadNext(matfp)) ) {
        Mat_VarPrint(matvar, 1);
        Mat_VarFree(matvar);
    }

    Mat_Close(matfp);
    return EXIT_SUCCESS;
}
.Ed
.Sh SEE ALSO
.Xr Mat_VarRead 3 ,
.Xr Mat_VarReadNextInfo 3 ,
.Xr Mat_VarPrint 3