language design - C function call followed by a comma separator -

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• what comma operator , do? 8 answers

i reading material errors should avoided when writing c programs , came across following code:

#include <stdio.h>  void foo(int param) {   printf("foo called\n");   printf("%d\n",param); }  int main() {   return foo,(1); } 

the code above build without errors , warnings (it show warning when -wall activated) when run small program nothing displayed. function foo not called because of comma separator.

my question why c standard allow such syntax? shouldn't compiler issue error in case? in context syntax used in real use case?

thanks in advance,

pd: i'm using gcc 4.8.3

edit:

couldn't compiler in case detect situation , issue error instead of warning (as said appears when -wall enabled)

c simple, minimalist language programmer supposed know they're doing.

in c, types convert each other quite , original c didn't have function declarations -- programmer supposed know how call each function , parameters.

c programming language unix ,

"unix not designed stop doing stupid things, because stop doing clever things."—doug gwyn (https://en.wikiquote.org/wiki/unix)

as bonus, if compiler doesn't try smart, compilation can fast.

c++ takes different approach this.

as practical applications of , operator, take at: https://en.wikipedia.org/wiki/comma_operator

the comma operator has relatively limited use cases. because discards first operand, useful first operand has desirable side effects. further, because used outside of specific idioms, , mistaken other commas or semicolon, potentially confusing , error-prone. nevertheless, there circumstances commonly used, notably in loops , in sfinae (http://en.cppreference.com/w/cpp/language/sfinae). embedded systems may have limited debugging capabilities, comma operator can used in combination macro seamlessly override function call, insert code before function call.