Parentheses around return value while calling the function in C

Question

During calling of this fucntion what is the purpose of adding parentheses around void here?

  //Declaration
  Std_ReturnType IsoMgr_WriteErrorCode(/*IN*/const IsoMgr_ErrorCode_t ErrorCode);
  //Calling Instance
  (void)IsoMgr_WriteErrorCode(ErrorCode);

It may be an explicit indication by the programmer that the return value is not used. — Paul Ogilvie, Oct 13 '16 at 13:31
@MichaelWalz `Std_ReturnType IsoMgr_WriteErrorCode(/*IN*/const IsoMgr_ErrorCode_t ErrorCode);` where `Std_ReturnType` is `uint8` — Has9, Oct 13 '16 at 13:47
Your title is very missleading! This is not even specific for function calls, but also used to suppress warnings for unused variables (not recommended) and function parameters (e.g. for dummy-functions). — too honest for this site, Oct 13 '16 at 13:50
it is missleading because I didn't know about return type casting, Isn't it the point of stackoverflow to direct people in right direction? — Has9, Oct 28 '16 at 13:12

score 3 · Answer 1 · answered Oct 13 '16 at 13:31

3

Some compilers may emit warnings when the return value of a function is not used.

This is a way to silence these warnings. It has no other purpose, and has no effect on the produced machine code.

answered Oct 13 '16 at 13:31

Macmade

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score 0 · Answer 2 · answered Oct 13 '16 at 13:50

When you write

IsoMgr_WriteErrorCode(ErrorCode);

This line will ignore return value if any. Compiler don't know whether you as programmer are aware of this particular thing so warnings may be generated.

By writing void before function you inform compiler that you know you are ignoring return value and so want to emit any warnings due to that.

(void)IsoMgr_WriteErrorCode(ErrorCode);

Parentheses around return value while calling the function in C

2 Answers2