Rule 14.4 and the explanation is not enough to understand why

[xiangke]

MISRA C 2012 guideline says:
Strong typing requires the controlling expression of an if statement or iteration-statement to have
essentially Boolean type.

For example:
typedef unsigned short tudtKalEvents;
#define udtSTOP_EVENT (tudtKalEvents)0x0001;

Code:

if(udtEvents & (tudtKalEvents) udtSTOP_EVENT)
  {
        vidStop();
  }

I think the code is ok, I use the & statement as the conditional expression. As we know, the value is not equal to zero, the condition shall be judged to be true,
why We must use the boolean type?

[dg1980]

Just to be clear, you don't need to use the boolean type, but you need to form a boolean expression, e.g.

Code:

if ((udtEvents & (tudtKalEvents)udtSTOP_EVENT) != 0u)
{
  vidStop();
}

It´s all about avoiding implicit conversion as much as possible.

[misra-c]

MISRA-C introduces a strong typing model to help users avoid unexpected issues which occur in the C typing model.
The rule prevents the accidental use of integer expression when a boolean expression was intended.

To be compliant with MISRA rule 14.4 you should write your test as a boolean expression:

Code:

if((udtEvents & udtSTOP_EVENT) != 0U  )