性能：else if vs if在函数中已经返回

Question

Is there any difference in performance between using else if / if in a function that returns something? I mean, if the function already returned, it won't execute the next if anyways, which is the purpose of else if, right? I wrote a small code snippet to illustrate that

#include <iostream>

bool foo(int x)
{
if (x == 3) return 1;
else if (x == 4) return 1; //using only if here has the performance of else if?
return 0;
}

int main()
{
int x = 4;
std::cout << foo(x);
std::cin.get();
return 0;
}

Answer 1

it should all be the same, one way to check for better performace is to compare your assembly code, you can use tools like godbolt.org, usually the code that generates fewer instructions performs faster.

by the way, it is better if you compare for "return 0" before the other two cases, as almost 100% of the times your input argument is not 3 or 4,

if (x != 3) return 0;
return 1;

is much better than

if (x == 3) return 1; 
return 0;