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.Dd April 21, 2011
.Dt MAT_VARREADNEXTINFO 3
.Os
.Sh NAME
.Nm Mat_VarReadNextInfo
.Nd Reads the information for the next variable in a MATLAB MAT file.
.Sh SYNOPSIS
.Fd #include <matio.h>
.Ft matvar_t *
.Fo Mat_VarReadNextInfo
.Fa "mat_t *matfp"
.Fc
.Sh DESCRIPTION
The
.Fn Mat_VarReadNextInfo
function reads the information 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_VarReadNextInfo
to read the information about each variable in the file.
For each variable read, the name, size, and class are printed in a format
similar to the MATLAB whos command.
.Bd -literal
#include <stdlib.h>
#include <stdio.h>
#include "matio.h"

static char *mxclass[16] = {"cell", "struct", "object","char","sparse",
                            "double","single","int8", "uint8","int16","uint16",
                            "int32","uint32","int64","uint64","function"
                           };

int
main(int argc,char **argv)
{
    mat_t    *matfp;
    matvar_t *matvar;
    size_t    nbytes;
    int       i;
    char size[32] = {'\0',};

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

    printf("%-20s       %-10s     %-10s     %-18s\n\n","Name","Size","Bytes",
           "Class");
    while ( NULL != (matvar = Mat_VarReadNextInfo(matfp)) ) {
        printf("%-20s", matvar->name);
        if ( matvar->rank > 0 ) {
            int cnt = 0;
            printf("%8d", matvar->dims[0]);
            for ( i = 1; i < matvar->rank; i++ ) {
                if ( ceil(log10(matvar->dims[i]))+1 < 32 )
                    cnt += sprintf(size+cnt,"x%d", matvar->dims[i]);
            }
            printf("%-10s",size);
        } else {
            printf("                    ");
        }
        printf("  %-18s\n",mxclass[matvar->class_type-1]);

        Mat_VarFree(matvar);
    }

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