# V616. Use of 'Foo' named constant with 0 value in bitwise operation.

The analyzer has detected use of a zero constant in the bitwise operation AND (&). The result of such an expression is always zero. It may lead to an incorrect logic of program execution when such an expression is used in conditions or loops.

Consider a simplest example:

    enum { FirstValue, SecondValue };
    int Flags = GetFlags();
    if (Flags & FirstValue)
    {...}

The expression in the 'if' operator's condition always equals zero. It causes an incorrect logic of program execution. Errors related to using zero constants in bitwise operations usually occur because of misprints or incorrect constant declaration. For example, it may appear that another constant should be used in such a fragment. This is the correct code:

    enum { FirstValue, SecondValue };
    int Flags = GetFlags();
    if (Flags & SecondValue)
    {...}

Another correct variant of this code is the following sample where the constant is declared as a non-zero constant. For example:

    enum { FirstValue = 1, SecondValue };
    int Flags = GetFlags();
    if (Flags & FirstValue)
    {...}

This diagnostic is classified as:

CWE-480

You can look at examples of errors detected by the V616 diagnostic.