#include <stdio.h>

int main()
{
int m, n, p, q, c, d, k, sum = 0;
int first[10][10], second[10][10], multiply[10][10];

printf("Enter the number of rows and columns of first matrix\n");
scanf("%d%d", &m, &n);
printf("Enter the elements of first matrix\n");

for ( c = 0 ; c < m ; c++ )
for ( d = 0 ; d < n ; d++ )
scanf("%d", &first[c][d]);

printf("Enter the number of rows and columns of second matrix\n");
scanf("%d%d", &p, &q);

if ( n != p )
printf("Matrices with entered orders can't be multiplied with each other.\n");
else
{
printf("Enter the elements of second matrix\n");

for ( c = 0 ; c < p ; c++ )
for ( d = 0 ; d < q ; d++ )
scanf("%d", &second[c][d]);

for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < q ; d++ )
{
for ( k = 0 ; k < p ; k++ )
{
sum = sum + first[c][k]*second[k][d];
}

multiply[c][d] = sum;
sum = 0;
}
}

printf("Product of entered matrices:-\n");

for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < q ; d++ )
printf("%d\t", multiply[c][d]);

printf("\n");
}
}

return 0;
}

Output

$ gcc matrix_multiply.c -o matrix_multiply
$ ./matrix_multiply

Enter the number of rows and columns of first matrix 3 3
Enter the elements of first matrix
1 2 0
0 1 1
2 0 1
Enter the number of rows and columns of second matrix 3 3
Enter the elements of second matrix
1 1 2
2 1 1
1 2 1
Product of entered matrices:-
5 3 4
3 3 2
3 4 5