Function to left shift a 2D array in C

Question

I\'m writing a function within my program to left shift all the numbers in an array that was passed to the function. An example is:

1 2 3 
4 5 6

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Answer 1

2-D arrays are contiguous in memory, so you can iterate over it as if it were a 1-D array:

void left_rotate(int array[][N])
{
    int *flat = (int *)array;
    int temp = flat[0];

    for ( size_t i = 1; i < M*N; ++i )
        flat[i-1] = flat[i];

    flat[M*N-1] = temp;

}

The for loop could also be replaced with a single block move:

memmove(&flat[0], &flat[1], (M*N-1) * sizeof *flat);