C++之值传递&指针传递&引用传递的示例详解

void Swap(int a, int b)
{
  int tmp = a;
  a = b;
  b = tmp;
}

#include <iostream>
 
void Swap(int a, int b)
{
    int tmp = a;
    a = b;
    b = tmp;
}
 
int main()
{
 
    int n = 0;
    int i = 1024;
 
    Swap(n, i);
    std::cout << "n: " << n << "\ni: " << i << std::endl;
 
    // 运行结果
    // n: 0
    // i: 1024
 
    return 0;
}
int n = 0;
int i = n; // i是n的值的副本
i = 42;

void SwapPoniter(int *a, int *b)
{
  int tmp = *a;
  *a = *b;
  *b = tmp;
}

#include <iostream>
 
void SwapPoniter(int *a, int *b)
{
    int tmp = *a;
    *a = *b;
    *b = tmp; // 修改了指针b指向的对象的值
    b = 0; // 只改变了函数体中的内存拷贝，实参并没有被修改
}
 
int main()
{
 
    int n = 0;
    int i = 1024;
    int *j = &n;
    int *k = &i;
 
    SwapPoniter(j, k);
    std::cout << "j: " << *j << "\nk: " << *k << std::endl;
 
    // 运行结果
    // j: 1024
    // k: 0
 
    return 0;
}
int n = 0, i = 1024;
int *p = &n, *q = &i;      // p指向n;q指向i
*p = 1024;                 // n的值被修改;p不变
p = q;                     // p现在指向了i;但是n与i的值都不变

void SwapQuote(int &a, int &b)
{
  int tmp = a;
  a = b;
  b = tmp;
}

#include <iostream>
 
void SwapQuote(int &a, int &b)
{
  int tmp = a;
  a = b;
  b = tmp;
}
 
int main()
{
 
  int n = 0;
  int i = 1024;
  
  SwapQuote(n, i);
  std::cout << "n: " << n << "\ni: " << i << std::endl;
    
  // 运行结果
  // n: 1024
  // i: 0
 
  return 0;
}

#include <iostream>
 
void testprint(const int &a)
{
  std::cout << "a: " << a << std::endl;
}
 
int main()
{
  int num = 111;
  testprint(num);
    // 输出结果 a: 111
 
  return 0;
}

void SwapQuote(int &a, int &b, int &mix, int &max)
{
  int tmp = a;
  a = b;
  b = tmp;
  a < b ? mix = a, max = b : max = a, mix = b;
}