将输入的字符串逆置。存在问题，代码如下，求修改！

#include
#include
#include
#define N 81
void fun(char *s)
{
char *p = s;
while(*p != '\0')
p++;
p--;
while(*p != '\0')
{
*(s++) = *p;
p--;
}
*s = '\0';
}
main()
{
char a[N];
printf("Enter a string：");
gets(a);
printf("\nThe original string is:");
puts(a);
fun(a);
printf("\nThe string after modified:");
puts(a);
strcpy(a,"Hello world!");
fun(a);
}

void fun(char *s)
{
char *p = s;
while(*p != '\0')
p++;
p--;
while(*p != '\0')
{
*(s++) = *p;
p--;
}
*s = '\0';
}
这个函数出了问题，经过这个函数处理之后S指针的位置在字符串的结尾，之后你再要PUTS的时候就出现问题了，
void fun(char *s)
{
char *p = s;
char *q = s;
while(*p != '\0')
p++;
p--;

while(*p != '\0')
{
*(s++) = *p;
p--;
}
*s = '\0';
}
s=q;

}

#include #include #include #include #define N 81 void fun(char *s) { char *p = s; char *q = s; while(*p != '\0') { p++; } p--; //p指针移动到s字符串的尾部 while(q < p) //q指向s字符串的头部，p指向s字符串的尾部，每次交换q和p所指地址的值，然后q，p同时向中间移动 { char temp = *q; *q = *p;; *p = temp; q++; p--; } } int main() { char a[N]; printf("Enter a string: "); gets(a); printf("\nThe original string is: "); puts(a); fun(a); printf("\nThe string after modified: "); puts(a); strcpy(a,"Hello world!"); puts(a); fun(a); puts(a); system("pause"); return 0; }