MAT_VARREADINFO(3)

💖 MAT_VARREADINFO(3) 💖

okay bestie, so this is a page from the Library Functions Manual — it's all about peeking at a variable in a MATLAB MAT file without actually hauling the whole thing into memory. iconic behaviour honestly.

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✨ NAME ✨

Mat_VarReadInfo — Reads the information for a specific variable in a MATLAB MAT file.

like, the metadata, the vibe, the receipts — not the whole payload.

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🌸 SYNOPSIS 🌸

#include <matio.h>

matvar_t *
Mat_VarReadInfo(mat_t *matfp, const char *name);

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🎀 DESCRIPTION 🎀

The Mat_VarReadInfo() function reads the information for the variable name in the open MAT file. that's it, that's the whole job. she's focused, she's lowkey efficient, she does one thing and she ate. 💅

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💫 RETURN VALUES 💫

• If the variable was found in the MAT file and the information about the variable was successfully read, you get back a pointer to the MATLAB variable structure. 🫶
• If the variable was not found, or there was an error reading the variable information, you get NULL. 😭

so basically: non-NULL = slay, NULL = check yourself before you wreck yourself.

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🌈 EXAMPLES 🌈

here's the whole thing, exactly as it is, no notes:

#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 %s0, argv[1]);
        return EXIT_FAILURE;
    }

    matvar = Mat_VarReadInfo(matfp, "x");
    if ( NULL != matvar ) {
        Mat_VarPrint(matvar);
        Mat_VarFree(matvar);
    }

    Mat_Close(matfp);
    return EXIT_SUCCESS;
}

okay so walk with me: open the file read-only (MAT_ACC_RDONLY), bail out with EXIT_FAILURE if that failed, grab the info for the variable named "x", and if we actually got something back — print it, free it, no memory leaks in this household — then close the file and return EXIT_SUCCESS. main character energy fr fr. ✨

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👑 SEE ALSO 👑

• Mat_VarRead(3)
• Mat_VarReadNextInfo(3)
• Mat_VarPrint(3)

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🌸 bestie reminder: this page ships with Debian, dated September 12, 2019. that's the version and the date, so now you know exactly which era of the docs you're reading. no cap. 🦋

stay hydrated, read your structs, and remember — NULL checks are self care. 💜🧚‍♀️