# V535. The 'X' variable is used for this loop and outer loops.

The analyzer detected a potential error: a nested loop is arranged by a variable which is also used in an outer loop.

In a schematic form, this error looks in the following way:

    size_t i, j;
    for (i = 0; i != 5; i++)
      for (i = 0; i != 5; i++)
        A[i][j] = 0;

Of course, this is an artificial sample, so we may easily see the error, but in a real application, the error might be not so apparent. This is the correct code:

    size_t i, j;
    for (i = 0; i != 5; i++)
      for (j = 0; j != 5; j++)
        A[i][j] = 0;

Using one variable both for the outer and inner loops is not always a mistake. Consider a sample of correct code the analyzer won't generate the warning for:

    for(c = lb; c <= ub; c++)
    {
      if (!(xlb <= xlat(c) && xlat(c) <= ub))
      {
        Range * r = new Range(xlb, xlb + 1);
        for (c = lb + 1; c <= ub; c++)
          r = doUnion(
            r, new Range(xlat(c), xlat(c) + 1));
        return r;
      }
    }

In this code, the inner loop "for (c = lb + 1; c <= ub; c++)" is arranged by the "c" variable. The outer loop also uses the "c" variable. But there is no error here. After the inner loop is executed, the "return r;" operator will perform exit from the function.

This diagnostic is classified as:

CWE-691 CERT-MSC01-C

You can look at examples of errors detected by the V535 diagnostic.