C语言去除字符串首尾空格，trim()函数实现

系统管理员 2022-05-21 06:49 728阅读 0赞

C语言去除字符串首尾空格，trim()函数实现  
[https://blog.csdn.net/u013022032/article/details/50521465][https_blog.csdn.net_u013022032_article_details_50521465]

**C 库函数 - isspace()**  
[http://www.runoob.com/cprogramming/c-function-isspace.html][http_www.runoob.com_cprogramming_c-function-isspace.html]

**C 标准库 - `<ctype.h>`**

[http://www.runoob.com/cprogramming/c-standard-library-ctype-h.html][http_www.runoob.com_cprogramming_c-standard-library-ctype-h.html]

![这里写图片描述][70]  
![这里写图片描述][70 1]  
![这里写图片描述][70 2]

## ![这里写图片描述][70 3] ##

/* C语言去除字符串首尾空格，trim()函数实现 https://blog.csdn.net/u013022032/article/details/50521465 */
    
    
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <ctype.h>
    
    //去除尾部空白字符 包括\t \n \r 
    /* 标准的空白字符包括： ' ' (0x20) space (SPC) 空格符 '\t' (0x09) horizontal tab (TAB) 水平制表符 '\n' (0x0a) newline (LF) 换行符 '\v' (0x0b) vertical tab (VT) 垂直制表符 '\f' (0x0c) feed (FF) 换页符 '\r' (0x0d) carriage return (CR) 回车符 //windows \r\n linux \n mac \r */
    char *rtrim(char *str)
    {
        if (str == NULL || *str == '\0')
        {
            return str;
        }
    
        int len = strlen(str);
        char *p = str + len - 1;
        while (p >= str  && isspace(*p))
        {
            *p = '\0';
            --p;
        }
    
        return str;
    }
    
    
    //去除首部空格
    char *ltrim(char *str)
    {
        if (str == NULL || *str == '\0')
        {
            return str;
        }
    
        int len = 0;
        char *p = str;
        while (*p != '\0' && isspace(*p))
        {
            ++p;
            ++len;
        }
    
        memmove(str, p, strlen(str) - len + 1);
    
        return str;
    }
    
    //去除首尾空格
    char *trim(char *str)
    {
        str = rtrim(str);
        str = ltrim(str);
    
        return str;
    }
    
    void demo()
    {
        char str[] = " ab c \r \n \t";
        printf("before trim:%s\n", str);
        char *p = trim(str);
        printf("after trim:%s\n", p);
    }
    
    int main(int argc, char **argv)
    {
        demo();
    
        return 0;
    }

--------------------

lbo@donglebuild2:~/lin/test$ ./a.out 
     efore trim:   ab  c 
    
    after trim:ab  c
    lbo@donglebuild2:~/lin/test$

[https_blog.csdn.net_u013022032_article_details_50521465]: https://blog.csdn.net/u013022032/article/details/50521465
[http_www.runoob.com_cprogramming_c-function-isspace.html]: http://www.runoob.com/cprogramming/c-function-isspace.html
[http_www.runoob.com_cprogramming_c-standard-library-ctype-h.html]: http://www.runoob.com/cprogramming/c-standard-library-ctype-h.html
[70]: /images/20220521/26d0f1c1073e440a9d88866e26e86829.png
[70 1]: /images/20220521/2aca6b66f0b043d7b82f5ee39bf4aaaf.png
[70 2]: /images/20220521/6274bfcf56574e30895b444245f98ef6.png
[70 3]: /images/20220521/cd954a24e05c49cdbbceff5917deb1ae.png