C++中使用sizeof查看几种数据类型所占内存字节大小

怼烎@ 2022-12-25 03:57 248阅读 0赞

### C++学习第一天 ###

*  sizeof
 *   *   *  整形类型
         *  浮点
         *  字符型
         *  sizeof其它用处

# sizeof #

在vs 2017环境中使用sizeof了解各个数据类型的大小

### 整形类型 ###

**short、int、long、long long**

#include <iostream>
    using namespace std;
    int main() {
    
    	cout << "short 类型所占内存空间为： " << sizeof(short) << endl;
    
    	cout << "int 类型所占内存空间为： " << sizeof(int) << endl;
    
    	cout << "long 类型所占内存空间为： " << sizeof(long) << endl;
    
    	cout << "long long 类型所占内存空间为： " << sizeof(long long) << endl;
    
    	system("pause");
    
    	return 0;
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center]

运行结果：  
![结果][20201130144712723.jpg_pic_center]  
补充：long在window系统下为4位字节；在Linux下32位为4个字节，64位为8个字节。  
所以有以下结论：  
字节大小顺序：short<int<=long<=long long;

### 浮点 ###

**float、double**

int main()
    {
    	cout << "float  sizeof = " << sizeof(float) << endl;
    	cout << "double sizeof = " << sizeof(double) << endl;
    
    	system("pause");
    	return 0;
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center 1]

运行结果：  
![结果][20201130145522497.jpg_pic_center]

### 字符型 ###

**char**

int main() {
    	cout << "char  sizeof = " << sizeof(char) << endl;
    	system("pause");
    	return 0;
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center 2]

运行结果：  
![在这里插入图片描述][20201130145915254.jpg_pic_center]

### sizeof其它用处 ###

我们还可以利用sizeof来计算整个数组所占内存空间的大小，还可以计算一个数组的元素个数。

#include <iostream>
    using namespace std;
    
    int sizeArray[] = {545,254,545,21,57,5,8,456,56,15,32,44,2,32,74,87,35,25,1,241,25,47,12,24,2,97,54,15,54,34};
    
    int main() {
    
    	cout << "整个数组所占空间为：" << sizeof(sizeArray) << endl;
    	cout << "数组元素个数为：" << sizeof(sizeArray) / sizeof(int) << endl;
    
    	system("pause");
    
    	return 0;
    }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center 3]

运行结果：  
![在这里插入图片描述][20201130150732826.jpg_pic_center]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/2ee9dbec95ec4c21aac16c919d6f3bc4.png
[20201130144712723.jpg_pic_center]: /images/20221120/7e26e1876626422d8cd12db9ee7656a4.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221120/446d8db70fed428ea64bc5628e248df6.png
[20201130145522497.jpg_pic_center]: /images/20221120/10021f8970164f0d95b6805a2caf3429.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221120/22192c7b9b4344d9910f98665e1f65f2.png
[20201130145915254.jpg_pic_center]: /images/20221120/6c514b77bac94fc5ace184b9932119a2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDMyODQxNA_size_16_color_FFFFFF_t_70_pic_center 3]: /images/20221120/fc5d6c8d0e4a4f5894c2785177dd3c46.png
[20201130150732826.jpg_pic_center]: /images/20221120/00173a5be28f42e18eb730bd9639799b.png