Find something wrong in this description?  Help us fix it! 
Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq

Why does PolySpace 5.1.1 (R2008a) show a red non-terminating loop (NTL) check in my code?

Sbicca Navarro Navarro Navarro BlackWhite Sbicca BlackWhite Sbicca zXaIn5Wq

Asked by MathWorks Support Team
on 27 Jun 2009

My C code looks as follows. When I run a PolySpace verification, the "for" keyword that is mentioned in the comments is marked red with a message that the loop never terminates. Also, I get another red check for a underflow error. I am using the option "-detect-unsigned-overflows".

int main () {
    int intC;
    unsigned int uintA, uintB, i = 0;
    uintA = 20;
    uintB = 30;
    intC = 10;
    // The following keyword "for" is marked with
    // a red NTL check.
    for(i; i < 10; i++) {
      // Subtraction marked with a red UNFL check
      // for a possible underflow.
      if ((uintA - uintB) < uintC) { // UNFL: 20 - 30
        //...
      }
    }
}

Tags

No tags entered yet.

Navarro Navarro BlackWhite Navarro Sbicca Sbicca BlackWhite Sbicca
LeatherBrown LeatherTan 1000 Zip Wolverine Black Mile Montague Leather q1zaX

1 Answer

Answer by MathWorks Support Team Navarro Sbicca BlackWhite Navarro Sbicca Navarro BlackWhite Sbicca on 27 Jun 2009
  Accepted Answer

The red NTL check is caused by the red underflow check (UNFL) within the loop. Correcting the code that causes the UNFL check or removing the option "-detect-unsigned-overflows" will cause the NTL check to disappear.

  0 Comments

Sign in to comment.