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C与C++编程一头一尾最重要, 无数英雄折腰, 多少豪杰翻船!

作者: Jerry Cat
时间: 2006/04/22
链接: http://www.cppblog.com/jerysun0818/archive/2006/04/22/6086.aspx

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//Fuction: BOOL revstr(char *str);
//Purpose: reverse a string
//Author:  Jerry
//Time:     04/22/2006
//Feature: This version is suitable for both sring and char array
char* revstr(char *str)
{
    int nCnt = 0, len = strlen(str);
    char* tmpstr = (char*) malloc(len+1);
    if     (tmpstr) strcpy(tmpstr, str);
    else { printf("\n malloc error!\n"); return 0; }
    for(--len, tmpstr = tmpstr + len; len > 0; *str++ = *tmpstr--, --len, ++nCnt);
    *str = *tmpstr; //C/C++编程一头一尾最重要, 无数英雄折腰, 多少豪杰翻船!
    free(tmpstr);
    return str - nCnt;
}

上面方法不好, 繁杂且易出错, 经沐枫兄指点, 下面俩是改进版^_^
char* revstr(char *str)
{
    char c, *head = str, *tail = str + strlen(str) -1;
    for(; head < tail; c = *head, *head++ = *tail, *tail-- = c);
    return str;
}

char* revstr(char *str)
{   //省去一变量, 时间换空间法
    char *head = str, *tail = str + strlen(str) -1;
    for(; head < tail; *head=*head ^ *tail, *tail=*head ^ *tail, *head=*head++ ^ *tail--);
    return str;
}