C++基础学习（三）之函数

Return_type Function_name(parameter list)
{
    body of the function
}

#include<iostream>
void main()
{
    void function(int a, int b);  //函数声明1
    //void function(int, int);  //函数声明2
    ...
    int x = 15, y = 20;
    function(x, y);  //函数调用，x、y为实参（实际参数）
}
void function(int a, int b)  //a、b为形参（形式参数）
{
    ...
}

//function.cpp
#include<iostream>
void function()
{
    ...
}

//main.cpp
#include<iostream>
void function();  //函数声明
void main()
{
    ...
    function();  //函数调用
    ...
}

//function.h
#include<iostream>
void function();

//function.cpp
#include"function.h"
void function()
{
    ...
}

//main.cpp
#include<iostream>
#include"function.h"
void main()
{
    ...
    function();  //函数调用
    ...
}

#include<iostream>
using namespace std;

void swap(int *x, int *y)  //参数互换
{
    int temp;
    temp = x;
    x = y;
    y = temp;
}
int main()
{
    int a = 10, b = 20;
    cout << a << endl << b << endl;
    
    swap(&a, &b);
    cout << a << endl << b << endl;

    return 0;
}

#include<iostream>
using namespace std;

void swap(int &x, int &y)  //参数互换
{
    int temp;
    temp = x;
    x = y;
    y = temp;
}
int main()
{
    int a = 10, b = 20;
    cout << a << endl << b << endl;
    
    swap(a, b);
    cout << a << endl << b << endl;

    return 0;
}

#include<iostream>

int function(int a, int b = 10)  //形参b赋予默认值10，如果函数调用过程中实参为空，则使用默认参数10
{
    ...
}

int main()
{
    ...
    function(x, y);
    function(x, );
    ...
}