C语言编程（在线等）

找吃艰难呀:
#include "stdio.h"
int main()
{
char a[]="ABCD1234efgh";
int l=strlen(a);
char c;
char *x=a;
char *y=a+l-1;
for(;x<y;++x,--y)
{c=*x;*x=*y;*y=c;}
printf("printf:\t%s\n",a);
}

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

int main(int argc, char *argv[])
{
char p[] = "ABCD1234efgh";
char *head = p;//指向字符串头
char *rear = p+strlen(p);//指向字符串尾的有效字符
rear--;//如果不-就指向\0了
char tmp;
while ( head<=rear )
{
tmp = *head;
*head = *rear;
*rear = tmp;
head++;
rear--;
}
printf("%s",p);
return 0;
}

#include <stdio.h>
#include <string.h>
int main()
{
int i;
char st[] = "ABCD1234efgh",tmp[20];