In a lot of industry standard coding practices (MISRA, CERT-C) that type of statement is prohibited and *will* result in an error being reported by the checker/scanner.

The if statement in your example has at least 2 errors from MISRA's perspective:

 * assignment within a conditional statement
 * the conditional not being a boolean type (that is you can't assume 0
   is false and non-0 is true...you actually need to compare...in this
   case against NULL)


On 1/29/21 3:59 PM, Fred Cisin via cctalk wrote:
On Fri, 29 Jan 2021, Chuck Guzis via cctalk wrote:

In the past (and occasionally today, I use the following construct:

FILE *myfile;

if ( !(myfile = fopen( filename, "r"))
{
 fprintf( stderr, "Couldn\'t open %s - exiting\n", filename);
 exit (1);
}

Yes, it only saves a line, but neatly describes what's being done.

--Chuck

Yes.
That is another excellent example of where you DO want to do an assignment AND a comparison (to zero).  A better example than my strcpy one, although yours does not need to save that extra line, but a string copy can't afford to be slowed down even a little.

That is why it MUST be a WARNING, not an ERROR.
Of course, the error is when that wasn't what you intended to do.

--
TTFN - Guy

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