MATLAB Application Program Interface Reference

Get a pointer to the dimensions array

#include "matrix.h"
const int *mxGetDimensions(const mxArray *array_ptr);

Arguments

array_ptr

Pointer to an mxArray.

Returns

The address of the first element in a dimension array. Each integer in the dimensions array represents the number of elements in a particular dimension. The array is not NULL-terminated.

Description

Use mxGetDimensions to determine how many elements are in each dimension of the mxArray that array_ptr points to. Call mxGetNumberOfDimensions to get the number of dimensions in the mxArray.

Example

Consider a MEX-file named GetSize that returns the size of each dimension of an input mxArray:

void
mexFunction(int nlhs,mxArray *plhs[],int nrhs,const mxArray 
*prhs[])
{
 int number_of_dims, c; 
 const int  *dim_array;

    number_of_dims = mxGetNumberOfDimensions(prhs[0]);
    dim_array = mxGetDimensions(prhs[0]);
    for (c=0; c<number_of_dims; c++)
       mexPrintf("%d\n", *dim_array++); 
}

In MATLAB, create a variable named my4d, then pass my4d to GetSize:

>> my4d = rand(3,5,2,4);

Call GetSize to return the size of each dimension in my4d:

>> GetSize(my4d)
3
5
2
4