Find something wrong in this description?  Help us fix it! 
Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA

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

Report Perry Perry BlackTan Perry Report Perry BlackTan Report BlackTan Report BlackTan Report qTwzxn8OA

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.

Report BlackTan Report Perry Report Perry BlackTan Report BlackTan BlackTan Perry Report Perry
Des Pieds Zohndra White Beige L'Amour WhiteBlack fT8qznw

1 Answer

Answer by MathWorks Support Team Perry BlackTan Perry Report Report Report Report BlackTan BlackTan BlackTan Report Perry Perry 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.