字符串逆序打印

版本1 两个指针从头到尾和从尾到头交换内容逆序

/***
str_reverse.c
***/
#include<stdio.h>
#include<string.h>int main()
{char buf[] = "abcdrfg";int len = strlen(buf);char *p1 = buf;char *p2 = buf + len - 1;while(p1 < p2){char c = *p1;*p1 = *p2;*p2 = c;++p1;--p2;}printf("buf = %s\n",buf);return 0; 
}

版本2

使用函数接口封装

/***
str_reverse.c
***/#include<stdio.h>
#include<string.h>int my_reverse(char *str)
{int iRet = -1;if(NULL == str){return iRet;    }char *buf = str;int len = strlen(buf);char *p1 = buf;char *p2 = buf + len - 1;while(p1 < p2){char c = *p1;*p1 = *p2;*p2 = c;++p1;--p2;}}int main()
{char buf[] = "abcdrfg";my_reverse(buf);printf("buf = %s\n",buf);return 0; 
}

版本三

使用栈特性将字符串存储到全局变量中

/***
str_reverse.c
***/#include<stdio.h>
#include<string.h>char g_buf[256];void reverse(char *p)
{if(NULL == p){return ;}if(*p == '\0'){return;}reverse(p+1);strncat(g_buf,p,1);
}int main()
{char buf[] = "abcd";memset(g_buf,0,sizeof(g_buf));reverse(buf);printf("g_buf = %s\n",g_buf);return 0;
}

版本4

使用栈将字符串存到传入的局部变量中

/***
str_reverse.c
***/#include<stdio.h>
#include<string.h>char g_buf[256];void reverse(char *p)
{if(NULL == p){return ;}if(*p == '\0'){return;}reverse(p+1);strncat(g_buf,p,1);
}int main()
{char buf[] = "abcd";memset(g_buf,0,sizeof(g_buf));reverse(buf);printf("g_buf = %s\n",g_buf);return 0;
}