The following example is nonvectorizable because it contains a conditional exit from the loop. In cases like this, you must rewrite the loop, if possible, for vectorization to succeed.

int a[99], b[99], c[99], i, n;
...
for (i = 0; i < n; i++)
{
     a[i] = b[i] + c[i];
     if (a[i] > 5) break;
};