source: CIVL/examples/loop_invariants/loop_assigns_given/arrayZeroes2d_column_preserve.cvl

#include<assert.h>

#pragma CIVL ACSL

$input int N;
$assume(N > 2);

int a[N][N];    

void arrayZeroes(int n) {
  int i;
  
  /*@ loop invariant 0 <= i && i <= n;
    @ loop invariant \forall int t; 0<=t && t<i ==> a[t][1] == 0;
    @ loop assigns   a[0 .. n-1][1], i;   
    @*/
  for (i = 0; i < n; i++) 
    a[i][1] = 0;
    
}

int main() {
  $havoc(&a);
  a[0][2] = 1;
  arrayZeroes(N);
  $assert($forall (int i : 0 .. N-1) a[i][1] == 0);
  $assert(a[0][2] == 1);
}