What is the “assert” function?

Question

I\'ve been studying OpenCV tutorials and came across the assert function; what does it do?

Answer 1

Stuff like 'raises exception' and 'halts execution' might be true for most compilers, but not for all. (BTW, are there assert statements that really throw exceptions?)

Here's an interesting, slightly different meaning of assert used by c6x and other TI compilers: upon seeing certain assert statements, these compilers use the information in that statement to perform certain optimizations. Wicked.

Example in C:

int dot_product(short *x, short *y, short z)
{
  int sum = 0
  int i;

  assert( ( (int)(x) & 0x3 ) == 0 );
  assert( ( (int)(y) & 0x3 ) == 0 );

  for( i = 0 ; i < z ; ++i )
    sum += x[ i ] * y[ i ];
  return sum;
}

This tells de compiler the arrays are aligned on 32-bits boundaries, so the compiler can generate specific instructions made for that kind of alignment.