Mat_VarCreateStruct2(3) Library Functions Manual Mat_VarCreateStruct2(3)
NAME
Mat_VarCreateStruct2 - Creates a structure variable.
SYNOPSIS
#include <matio.h>
matvar_t *
Mat_VarCreateStruct(const char *name, int rank, const size_t *dims,
const char *const *fields);
DESCRIPTION
The Mat_VarCreateStruct2() function creates a structure variable named
name that can be written to a MAT file.
RETURN VALUES
If the structure variable was successfully created, a pointer to the
variable is returned. Otherwise NULL is returned. The structure
variable pointer should be free'd when no longer needed using
Mat_VarFree(). The names of the fields are copied in the function, and
thus should be released after calling the function if necessary. The
names of the fields has to be a NULL-terminated array.
EXAMPLES
This example program opens a MAT file named by the first argument to the
program, and writes a structure named a to the file.
#include "matio.h"
int
main(int argc, char **argv)
{
mat_t *matfp;
matvar_t *matvar;
matvar_t *field;
const char *fields[3] = {"field1", "field2", NULL};
double data1 = 1, data2 = 2;
size_t dims[2] = {1, 1};
matfp = Mat_Open(argv[1], MAT_ACC_RDWR);
if ( NULL == matfp ) {
fprintf(stderr, "Error opening MAT file %s0, argv[1]);
return EXIT_FAILURE;
}
dims[0] = 1; dims[1] = 1;
matvar = Mat_VarCreateStruct2("a", 2, dims, fields);
if ( NULL == matvar ) {
Mat_Close(matfp);
return EXIT_FAILURE;
}
field = Mat_VarCreate(NULL, MAT_C_DOUBLE, MAT_T_DOUBLE, 2, dims, &data1,
MAT_F_DONT_COPY_DATA);
Mat_VarSetStructFieldByName(matvar, "field1", 0, field);
field = Mat_VarCreate(NULL, MAT_C_DOUBLE, MAT_T_DOUBLE, 2, dims, &data2,
MAT_F_DONT_COPY_DATA);
Mat_VarSetStructFieldByName(matvar, "field2", 0, field);
Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_NONE);
Mat_VarFree(matvar);
Mat_Close(matfp);
return EXIT_SUCCESS;
}
SEE ALSO
Mat_VarCreate(3), Mat_VarSetStructFieldByName(3)
macOS 15.7 January 5, 2026 macOS 15.7
matio 1.5.30 - Generated Wed Jan 7 07:44:25 CST 2026