Write a C program to multiply two matrices

Are you sure you know this? A lot of people think they already know this, but guess what? So take a good look at this C program. Its asked in most of the interviews as a warm up question.
// Matrix A (m*n)
// Matrix B (n*k)
// Matrix C (m*k)
for(i=0; i<m; i++)
{
for(j=0;j<k;j++)
{
c[i][j]=0;
for(l=0;l<n;l++)
c[i][j] += a[i][l] * b[l][j];
}
}