char *revstr(char *str)
{
char ch;
char *left=str;
char *start=str;
while(*str!='\0')
{
str++;
}
str--;
if(left<str)
{
ch=*str;
*str=*left;
*left=ch;
left++;
str--;
}
return start;

}

main()
{
char *p="aaabbcc";
char *out;
out=revstr(p);
printf("%s\n",out);
}
大家能帮我看看这个程序有什么问题吗？谢谢

[此贴子已经被作者于2006-11-13 11:21:23编辑过]

while(*str!='\0')
{
str++;
}
最后str不是应该指向'\0'吗？

但你把它最后一个字符('\0')给start的第一个字符.这个是字符串结束符.所以没有输出.

说错了,应该叫输出为空.

Do you notice this expression : char *p="aaabbcc" ? So, the p_pointer points to an address where is in the static memory.And you can't change the value of the string "aaabbcc" for it is stored in the static memory.
So you have to modify this expression.Try to write "char p[] = "aaabbcc" to instead of the wrong expression.

while(*str!='\0')
{
str++;
}
最后str不是应该指向'\0'吗？
==================
That's right.

if(left<str)
{
ch=*str;
*str=*left;
*left=ch;
left++;
str--;
}
================

It is not neccesory to define ch for exchanging *str and *left. But the code in the if branch can't solve your problem for that left_pointer and str_pointer point to the same string.I mean, if you change the value of *str, and the value of the array will change also. So you can't reverse the string.

是的，深刻同意楼上的，
if(left<str)
{
ch=*str;
*str=*left;
*left=ch;
left++;
str--;
}

if要改成while。就ok了。