C - scanf

r囧r小猫 2022-09-01 15:43 223阅读 0赞

#  C - scanf #

int scanf ( const char * format, ... );

## Read formatted data from stdin ##

Reads data from stdin and stores them according to the parameter `format` into the locations pointed by the additional arguments.  
从 stdin 读取数据并根据 `format` 参数将它们存储到附加参数指向的位置。

The additional arguments should point to already allocated objects of the type specified by their corresponding format specifier within the `format` string.  
附加参数应指向已分配的对象，其类型由 `format` 字符串中的相应格式说明符指定。

## Return Value ##

On success, the function returns the number of items of the argument list successfully filled. This count can match the expected number of items or be less (even zero) due to a matching failure, a reading error, or the reach of the end-of-file.  
成功时，该函数返回成功填充的参数列表的项目数。由于匹配失败、读取错误或到达文件末尾，此计数可能与预期的项目数匹配或更少 (甚至为零)。

If a reading error happens or the end-of-file is reached while reading, the proper indicator is set (feof or ferror). And, if either happens before any data could be successfully read, EOF is returned.  
如果在读取时发生读取错误或到达文件末尾，则会设置正确的指示符 (feof or ferror)。并且，如果在任何数据可以成功读取之前发生任何一种情况，则返回 EOF。注意返回值是 `int`。

If an encoding error happens interpreting wide characters, the function sets `errno` to `EILSEQ`.  
如果在解释宽字符时发生编码错误，该函数会将 `errno` 设置为 `EILSEQ`。

## Example ##

//============================================================================
    // Name        : Yongqiang Cheng
    // Author      : Yongqiang Cheng
    // Version     : Version 1.0.0
    // Copyright   : Copyright (c) 2020 Yongqiang Cheng
    // Description : Hello World in C++, Ansi-style
    //============================================================================
    
    #define _CRT_SECURE_NO_WARNINGS
    #include <stdio.h>
    
    int main()
    {
    	char str[80];
    	int i;
    
    	printf("Enter your family name: ");
    	scanf("%79s", str);
    
    	printf("Enter your age: ");
    	scanf("%d", &i);
    
    	printf("Mr. %s , %d years old.\n", str, i);
    	printf("Enter a hexadecimal number: ");
    	scanf("%x", &i);
    	printf("You have entered %#x (%d).\n", i, i);
    
    	return 0;
    }

Enter your family name: yongqiang
    Enter your age: 29
    Mr. yongqiang , 29 years old.
    Enter a hexadecimal number: ff
    You have entered 0xff (255).
    请按任意键继续. . .

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5neXExMTY_size_16_color_FFFFFF_t_70_pic_center]

## Compatibility ##

Particular library implementations may support additional specifiers and sub-specifiers.  
特定的库实现可能支持额外的说明符和子说明符。

Those listed here are supported by the latest C and C++ standards (both published in 2011), but those in yellow were introduced by C99 (only required for C++ implementations since C++11), and may not be supported by libraries that comply with older standards.  
此处列出的内容受最新 C 和 C++ 标准 (均于 2011 年发布) 的支持，但黄色部分是由 C99 引入的 (自 C++11 以来仅 C++ 实现需要)，并且可能不受符合标准的库的支持旧标准。

## References ##

[https://cplusplus.com/reference/cstdio/scanf/][https_cplusplus.com_reference_cstdio_scanf]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5neXExMTY_size_16_color_FFFFFF_t_70_pic_center]: /images/20220829/be4920b8e94a4d6dbd966a410542de97.png
[https_cplusplus.com_reference_cstdio_scanf]: https://cplusplus.com/reference/cstdio/scanf/