7.2-function-overloading

Bilibili 7.2

1 background - Different types of rounding -C and C++ The implementation of the

2 Function overload implementation function overloading fulfillment

• The compiler will preform name lookup
• Argument-dependent lookup, also known as ADL.
• The return type will not be considered in name lookup.

That is to say, The same function must be a function with the same function name and parameter list .

3 Instance to explain

#include <iostream>

using namespace std;

int sum(int x, int y)
{
    cout << "sum(int, int) is called" << endl;
    return x + y;
}
float sum(float x, float y)
{
    cout << "sum(float, float) is called" << endl;
    return x + y;
}
double sum(double x, double y)
{
    cout << "sum(double, double) is called" << endl;
    return x + y;
}

// //Is the following definition correct?
// double sum(int x, int y)
// {
//     cout << "sum(int, int) is called" << endl;
//     return x + y;
// }

int main()
{

    cout << "sum = " << sum(1, 2) << endl;
    cout << "sum = " << sum(1.1f, 2.2f) << endl;
    cout << "sum = " << sum(1.1, 2.2) << endl;

    //which function will be called?
    cout << "sum = " << sum(1, 2.2) << endl;

    return 0;
}

Two examples mentioned in the teacher's class

• One is the same function name , The input parameters are the same , The return parameters are different , This is function redefinition , Compiler error .
• Another example is when the parameter types are different , If there are multiple functions , The compiler will report an error . But if there is only one function , Don't complain .

point

Function overloading can reduce the memory burden of programmers .