Question

Why this piece of code compiles?

#include <iostream>

int foo(int x)
{
   if(x == 10)
     return x*10;
}

int main()
{
int a;
std::cin>>a;
std::cout<<foo(a)<<'\n';
}

The compiler shouldn’t give me an error like “not all code paths returns a value”? What happens/returns my function when x isn’t equal to ten?

Answer 1

The result is undefined, so the compiler is free to choose — you probably get what happens to sit at the appropriate stack address where the caller expects the result. Activate compiler warnings, and your compiler will inform you about your omission.