C Programming

To ensure that programs are "correct", it must be usefull to use assertions as illustrated below:

#include <assert.h>

void play(char c,int p) {
  // Precondition
  assert((c=='X') || (c=='O'));
  assert((cells[p]==' '));
  assert((p>=0) && (p<DIM*DIM));
  if(cells[p]==' ') cells[p] = c;
  // Postcondition
  assert(cells[p]==c);
}

void main() {
  init();
  play('A',1);
}