Demonstrates how to allocate a 2D array in C, populating it with uniform random numbers. You can use the notation A[i][j] to access its elements

array2d.c

/*
Example demonstrating how to allocate and use a multdimensional 
array.

Reference: http://pleasemakeanote.blogspot.com.br/2008/06/2d-arrays-in-c-using-malloc.html
*/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>


// Method to allocate a 2D array of floats
float** make_2d_array(int nx, int ny) {
	float** arr;

	arr = (float**) malloc(nx*sizeof(float*));
	
	for (int i = 0; i < nx; i++)
		arr[i] = (float*) malloc(ny*sizeof(float));
	
	return arr;
} 



int main(int argc, char *argv[])
{
	int i, j;
	size_t N1=100,N2=200;

	// allocates 2D array
	float **ran = make_2d_array(N1, N2);

	// initialize pseudo-random number generator
    srand(time(NULL)); 

	// populates the array with random numbers
    for (i = 0; i < N1; i++){
    	for (j=0; j<N2; j++) {
    		ran[i][j] = ((float)rand()/(float)(RAND_MAX));
    	}
   }

	// prints values
	for (i=0; i<N1; i++) {
		for (j=0; j<N2; j++) {
			printf("A[%d][%d] = %f \n", i,j,ran[i][j]);
		}
	}

	free(ran);
}