How does the efficiency of C++ function overloading compare?

Function overloading will not affect efficiency. The C compiler determines which function to call through name resolution at compile time, introducing no overhead at runtime.

C Efficiency comparison of function overloading

Function overloading means that multiple functions with the same name are allowed in the same class or namespace. They are distinguished only by the parameter list. Function overloading is a common feature in C that improves code readability and maintainability.

However, some people question the efficiency of function overloading. Let us explore the efficiency impact of function overloading through a practical case.

#include <iostream>

using namespace std;

// 原始函数
int sum(int a, int b) {
    return a + b;
}

// 重载函数
double sum(double a, double b) {
    return a + b;
}

int main() {
    int x = 5;
    int y = 7;
    cout << sum(x, y) << endl; // 调用原始函数

    double u = 5.5;
    double v = 7.7;
    cout << sum(u, v) << endl; // 调用重载函数

    return 0;
}

Analysis:

In this example, we define two sum functions with the same name. The first function accepts two integer parameters and returns an integer result, and the second function accepts two double-precision floating-point parameters and returns a double-precision floating-point result.

When we call sum(x, y), the compiler will give priority to the original function that accepts two integer parameters. This is because in C, the compiler prioritizes exact matches over type conversions.

When we call sum(u, v), the compiler will choose the overloaded function that accepts two double-precision floating point arguments. This is because the compiler cannot implicitly convert these two double-precision floating-point parameters to integers.

So, will function overloading affect efficiency?

The answer is: No.

The C compiler performs name resolution during compilation, which determines the function to be called. In our example, the compiler determines at compile time whether to call the original function or the overloaded function. This means that function overloading does not introduce any additional overhead at runtime.

Thus, function overloading is an efficient and useful feature in C that does not negatively affect efficiency.

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