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// assert() example by gbmhunter for www.mbedded.ninja
// Designed as an example of assert() for embedded systems.
// See http://w...content-available-to-author-only...d.ninja/programming/languages/c/assertions-assert
 
#include <stdio.h>
#include <stdbool.h>
 
// Comment out to disable asserts
#define DEBUG
 
// We will use captial letters for ASSERT to differentiate it from the system-provided
// assert() if it exists.
#ifdef DEBUG
	#define ASSERT(exp)  ((void)(exp), (exp ? : AssertFailed(__FILE__, __LINE__, #exp)))
#else
	#define ASSERT(exp) (void)(0);
#endif
 
//! @brief		Assert failed handling function.
//! @details	This will be called by the ASSERT() macro.
void AssertFailed(const char * filename, int lineNumber, const char * expression) {
	printf("%s, line %i: Assertion \"%s\" failed.\r\n", filename, lineNumber, expression);	
}
 
int main(void) {
 
	// Some really basic (and useless) assert() tests
	ASSERT(true);
	ASSERT(false);
 
	// Some more practical assert tests
	int x = 3;
 
    ((void)(x = 7), x==7 ? x = 4: x = 2);
	ASSERT(x == 3);
	ASSERT(x == 4);
 
	// An assert() with an embedded assignment should
	// give a compiler error.
	//ASSERT(x = 1);
 
	return 0;
}

prog.c: In function ‘main’:
prog.c:34:37: error: lvalue required as left operand of assignment
     ((void)(x = 7), x==7 ? x = 4: x = 2);
                                     ^
prog.c:14:44: warning: the omitted middle operand in ?: will always be ‘true’, suggest explicit middle operand [-Wparentheses]
  #define ASSERT(exp)  ((void)(exp), (exp ? : AssertFailed(__FILE__, __LINE__, #exp)))
                                            ^
prog.c:35:2: note: in expansion of macro ‘ASSERT’
  ASSERT(x == 3);
  ^~~~~~
prog.c:14:44: warning: the omitted middle operand in ?: will always be ‘true’, suggest explicit middle operand [-Wparentheses]
  #define ASSERT(exp)  ((void)(exp), (exp ? : AssertFailed(__FILE__, __LINE__, #exp)))
                                            ^
prog.c:36:2: note: in expansion of macro ‘ASSERT’
  ASSERT(x == 4);
  ^~~~~~

Standard output is empty