值传递、地址传递和引用传递

旧城等待， 2021-09-25 08:08 516阅读 0赞

### 文章目录 ###

*  值传递
 *  地址传递
 *  引用传递
 *  原理
 *  总结

# 值传递 #

值传递，形参是实参的一份拷贝。

交换两个数

#include <iostream>
    
    void swap(int a, int b)
    { 
    	int temp = a;
    	a = b;
    	b = temp;
    }
    
    int main()
    { 
    	int a = 1, b = 2;
    	
    	std::cout << "a = " << a << ", b = " << b << std::endl;	
    	swap(a, b);
    	std::cout << "a = " << a << ", b = " << b << std::endl;
    	return 0;
    }

结果：交换未成功  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1B1cnN1ZUx1bw_size_16_color_FFFFFF_t_70]

# 地址传递 #

地址传递，形参指向实参变量。

交换两个数

#include <iostream>
    
    void swap(int *a, int *b)
    { 
    	int temp = *a;
    	*a = *b;
    	*b = temp;
    }
    
    int main()
    { 
    	int a = 1, b = 2;
    	
    	std::cout << "a = " << a << ", b = " << b << std::endl;	
    	swap(&a, &b);
    	std::cout << "a = " << a << ", b = " << b << std::endl;
    	return 0;
    }

结果：交换成功  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1B1cnN1ZUx1bw_size_16_color_FFFFFF_t_70 1]

# 引用传递 #

引用传递，形参是实参的别名，本质上是同一个东西。

交换两个数

#include <iostream>
    
    void swap(int &a, int &b)
    { 
    	int temp = a;
    	a = b;
    	b = temp;
    }
    
    int main()
    { 
    	int a = 1, b = 2;
    	
    	std::cout << "a = " << a << ", b = " << b << std::endl;	
    	swap(a, b);
    	std::cout << "a = " << a << ", b = " << b << std::endl;
    	return 0;
    }

结果：交换成功  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1B1cnN1ZUx1bw_size_16_color_FFFFFF_t_70 2]

# 原理 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1B1cnN1ZUx1bw_size_16_color_FFFFFF_t_70 3]

# 总结 #

地址传递和引用传递可以在函数中修改到外部的变量。

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