linux c 实现函数 trim 除去字符串首尾空格

Love The Way You Lie 2021-09-03 07:16 443阅读 0赞

Trim()函数功能除去字符串开头和末尾的空格或其他字符，函数执行成功时返回删除了字符串首部和尾部空格的字符串。

char *trim(char *str)

C语言标准库中并没有trim()函数，比较遗憾，那么我们就来实现一个

一、 具体实现代码

#include <string.h>
    #include <stdio.h>
    #include <ctype.h>
     
    // delete the front whitespace
    char *left_trim(char *str)
    {
        char *beginp = str;
        char *tmp = str;
        while(isspace(*beginp)) beginp++;
        while((*tmp++ = *beginp++));
     
        return str;
    }
     
    // delete the back whitespace
    char *right_trim(char *str)
    {
        char *endp;
        size_t len = strlen(str);
     
        if(len == 0) return str;
     
        endp = str + strlen(str) - 1;
        while(isspace(*endp)) endp--;
        *(endp + 1) = '\0';
     
        return str;
    }
     
    char *trim(char *str)
    {
        str = left_trim(str);
        str = right_trim(str);
     
        return str;
    }
     
    int main(void)
    {
        char *src[] =
        {
            "   hello world   ",
            "    hello world",
            "hello world   ",
            "hello world",
            "",
            NULL
        };
        char result[1024];
         
        for(int index = 0; src[index] != NULL; index++)
        {
            strcpy(result, src[index]);
            printf("[%s] -> [%s]\n", src[index], trim(result));          
        }
     
        return 0;
    }

二、 运行结果

[ycxie@fedora Workspace]$ gcc string_trim.c -o string_trim -Wall
    [ycxie@fedora Workspace]$ ./string_trim
    [   hello world   ] -> [hello world]
    [    hello world] -> [hello world]
    [hello world   ] -> [hello world]
    [hello world] -> [hello world]
    [] -> []