C++-函数重载(reload), 函数定义声明(void func(int))

对于相同的函数名字，根据其输入的变量不同进行函数重载

/*
根据函数的输入变量不同进行函数重载
*/
#include <iostream>

using namespace std; 


void foo(int i) {
    cout << "int foo(int i)" << endl; 
}

void foo(int i, int j) {
    cout << "void foo(int i, int j)" << endl; 
}

void foo(int i, double j) {
    cout << "void foo(int i, double j)" << endl; 
}

int main(void) {
    int a = 0; 
    double b = 0; 
    foo(a, b); 
    return 0; 
    
} 

对于函数重载，如果char->int 表示向上采样, short -> char 表示向下采样

/*
变量不匹配进行重载 
*/
#include <iostream>

using namespace std; 


void func(int i) {  // char - > int 
    cout << "func(1)" << endl; 
}


void func(const char i) {  // char - > const char 
    cout << "func(2)" << endl; 
}

//sort->char 降级匹配 
void foo(char i) {
    cout << "foo(1)" << endl; 
}
//sort->int 升级匹配 
void foo(int i) {
    cout << "foo(2)" << endl; 
}
//省略匹配 
void hum(int i, ...) {
    cout << "hum(1)" << endl; 
}

//double->int 降级匹配 

void hum(int i, int j) {
    cout << "hum(2)" << endl; 
}


int main() {
    char c = 2; 
    func(c);

    short s = 2; 
    foo(s); 
    
    int i = 0; 
    double j = 0; 
    hum(i, j);  
}

在开头进行函数声明，同时定义变量，使得未输入的函数有初始值

/*
进行函数声明和变量预定义 
*/ 
#include <iostream>

using namespace std; 

//函数预声明 
void func(int a = 10, int b = 10, int c = 20);

int main(void) {
    func(11, 20, 30); 
    func(11, 20); 
    func(11); 
}

void func(int a, int b, int c) {
    cout << a << "," << b << "," << c << endl; 
}