【C语言补漏】数据类型

╰+哭是因爲堅強的太久メ 2022-04-21 15:18 231阅读 0赞

# 数据类型  #

变量在内存中所占坑的大小。

c语言下的数据类型

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![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BsU29uZ19DU0RO_size_16_color_FFFFFF_t_70 1][]

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# sizeof运算符 #

用于获得数据类型或表达式的长度

–sizeof(object);  //sizeof(对象);

–sizeof(type\_name);  //sizeof(类型);

–sizeof object;  //sizeof 对象;

示例程序：

#include<stdio.h>
    
    void main()
    {
    	int i;
    	char j;
    	float k;
    
    	i = 123;
    	j = 'c';
    	k = 3.14;
    
    	printf("size of int is: %d\n", sizeof(int));
    	printf("size of i is: %d\n", sizeof(i));
    	
    	printf("size of char is: %d\n", sizeof(char));
    	printf("size of int j is: %d\n", sizeof(j));
    
    	printf("size of float is: %d\n", sizeof(float));
    	printf("size of k is: %d\n", sizeof(k));
    }

运行结果：

> size of int is: 4  
> size of i is: 4  
> size of char is: 1  
> size of int j is: 1  
> size of float is: 4  
> size of k is: 4  
> 请按任意键继续. . .

示例程序：

#include<stdio.h>
    
    void main()
    {
    	printf("size of int is: %d\n", sizeof(int));
    	printf("size of short int is: %d\n", sizeof(short));
    	printf("size of long int is: %d\n", sizeof(long));
    	printf("size of long long int is: %d\n", sizeof(long long));
    	
    	printf("size of char is: %d\n", sizeof(char));
    
    	printf("size of _Bool is: %d\n", sizeof(_Bool));
    
    	printf("size of float is: %d\n", sizeof(float));
    	printf("size of double is: %d\n", sizeof(double));
    	printf("size of long double is: %d\n", sizeof(long double));
    }

运行结果：

> size of int is: 4  
> size of short int is: 2  
> size of long int is: 4  
> size of long long int is: 8  
> size of char is: 1  
> size of \_Bool is: 1  
> size of float is: 4  
> size of double is: 8  
> size of long double is: 8  
> 请按任意键继续. . .

变量在不同编译环境、操作系统下，占用的大小是不一样的，但是一定保证：

![20181127091325682.png][]

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# signed和unsigned  #

限定变量的范围，有符号和无符号。

•\[signed\] short \[int\]

•unsigned short \[int\]

•\[signed\] int

•unsigned int

•\[signed\] long \[int\]

•unsigned long \[int\]

•\[signed\] long long \[int\]

•unsigned long long \[int\]•

看看下面的程序，运行结果会出现什么效果：

#include<stdio.h>
    
    void main()
    {
    	short i;
    	unsigned short j;
    
    	i = -1;
    	j = -1;
    	printf("i = %d\n", i);
    	printf("j = %d\n", j);
    }

运行结果：

> i = -1  
> j = 65535  
> 请按任意键继续. . .

为什么会出现这样的结果？？？是因为取值范围出现问题。

unsigned short 类型的变量取值范围是：0~65535

超出的取值范围，所以。。。你懂得

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★finished by songpl,2018.11.27

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[20181127091325682.png]: /images/20220414/36835b1c7a2a4e78b984b96c74dd7fd6.png