assert

#include <iostream>
//#define NDEBUG //发行版本中，assert都会被关掉
#include <assert.h>

int main()
{
   int i = 10;
   assert(i > 20);

   return 0;
}

a.out: assert.cpp:7: int main(): Assertion `i > 20' failed.
Aborted (core dumped)