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MAT_VARREADNEXTINFO(3) Library Functions Manual MAT_VARREADNEXTINFO(3)

NAME

Mat_VarReadNextInfo — Reads the information for the next variable in a MATLAB MAT file.

SYNOPSIS

#include <matio.h>

matvar_t *
Mat_VarReadNextInfo(mat_t *matfp);

DESCRIPTION

The () function reads the information for the next variable stored in the open MAT file.

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.

EXAMPLES

This example program opens a MAT file named by the first argument to the program, and uses 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.

#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include "matio.h"

static char *mxclass[17] = {"cell", "struct", "object", "char", "sparse",
                            "double", "single", "int8", "uint8", "int16",
                            "uint16", "int32", "uint32", "int64", "uint64",
                            "function", "opaque"
                           };

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

    matfp = Mat_Open(argv[1], MAT_ACC_RDONLY);
    if ( NULL == matfp ) {
        fprintf(stderr, "Error opening MAT file %s0, argv[1]);
        return EXIT_FAILURE;
    }

    printf("%-32s%-16s%-16s%-16s0, "Name", "Size", "Bytes", "Class");
    while ( NULL != (matvar = Mat_VarReadNextInfo(matfp)) ) {
        printf("%-32s", matvar->name);
        if ( matvar->rank > 0 ) {
            int cnt;
            int i;
            cnt = snprintf(size, sizeof(size), "%zd", matvar->dims[0]);
            for ( i = 1; i < matvar->rank; i++ ) {
                if ( ceil(log10((double)matvar->dims[i])) + 1 < 32 ) {
                    cnt += snprintf(size + cnt, sizeof(size) - cnt,
                        "x%zd", matvar->dims[i]);
                    if ( cnt >= sizeof(size) ) {
                        break;
                    }
                }
            }
            printf("%-16s", size);
        } else {
            printf("                ");
        }
        snprintf(size, sizeof(size), "%zd", Mat_VarGetSize(matvar));
        printf("%-16s", size);
        printf("%-16s0, mxclass[matvar->class_type - 1]);

        Mat_VarFree(matvar);
    }

    Mat_Close(matfp);
    return EXIT_SUCCESS;
}

SEE ALSO

Mat_VarRead(3), Mat_VarReadInfo(3), Mat_VarReadNext(3)

March 4, 2024 Debian