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SA0081: Upper border is not a constant

Detects the FOR statements where the upper bound is not defined with a constant value

Justification: If the upper bound of a loop is a variable value, then it is no longer possible to see how often a loop is executed. This can result in serious problems at runtime. The worst case is an infinite loop.

Importance: High

Example 86. Example
PROGRAM PLC_PRG
VAR
    i:INT;
    iBorder1: INT := 10;
    iBorder2: INT := 10;
    iCounter: INT;
END_VAR
VAR CONSTANT
    ciBorder:INT := 10;
END_VAR

FOR i:=0 TO 10 DO    //OK
    iCounter := i;
END_FOR

FOR i:=0 TO ciBorder DO    // OK
    iCounter := i;
END_FOR

FOR i:=0 TO iBorder1 DO    // SA0081
    iCounter := i;
END_FOR

FOR i:=0 TO iBorder2 DO    // SA0081
    iCounter := i;
    IF iCounter = 10 THEN
        iBorder2 := 50;
    END_IF
END_FOR

Output in the Messages view:

  • sa_icon_message.png SA0081: Upper border of a for loop must be a constant value



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