V590. Consider inspecting this expression. The expression is excessive or contains a misprint

31.08.2011

The analyzer detected a potential error: there is an excessive comparison in code. Let me explain this by a simple example:

if (Aa == 10 && Aa != 3)

The condition will hold if 'Aa == 10'. The second part of the expression is meaningless. On studying the code, you may come to one of the two conclusions:

1) The expression can be simplified. This is the fixed code:

if (Aa == 10)

2) The expression has an error. This is the fixed code:

if (Aa == 10 && Bb != 3)

Here is an example of how this error may look in a real application:

int appliedSize, appliedSign;
...
if(appliedSize == 'b' && appliedSize != 's' && ...)
...

The expression has a misprint which is the reason why the appliedSize variable is used twice while appliedSign is not used at all. This is the fixed code:

int appliedSize, appliedSign;
...
if(appliedSize == 'b' && appliedSign != 's' && ...)
...

Let's study another example from practice. We have no error here, but the expression is excessive, which might make the code less readable:

while (*pBuff == ' ' && *pBuff != '\0')
  pBuff++;

The " *pBuff != '\0' " check is meaningless. This is the shortened code:

while (*pBuff == ' ')
  pBuff++;
You can look at examples of errors from real projects which were detected by this diagnostic message.