字符串倒序

#include <stdio.h>
#include <string.h>
#include <stack>
char *Strrev(char *s)
{
?char ch;
?char *p = s;
?char *q = s + strlen(s) - 1;
?while (p != q)
?{
? ch = *p;
? *p++ = *q;
? *q-- = ch;
?}
?return s;
}
char *Strrev_Recursion(char *s, char *p)
{
?if (s != p)
?{
? char ch = *s; *s = *p; *p = ch;
? Strrev_Recursion(++s, --p);
?}
?return --s;
}
char *_Strev(char *s)
{
?return Strrev_Recursion(s, s + strlen(s) - 1);
}

char *Strrev_WithoutRecursion(char *s)
{
?using std::stack;
?stack<char> aStack;
?char *p = s;
?while (*p != '/0')
? aStack.push(*p++);
?p = s;
?while (!aStack.empty())
?{
? *p++ = aStack.top();
? aStack.pop();
?}
?
?return s;
}
void main()
{
?char s[50] = "I am a student.";
?printf("%s/n", Strrev(s));
?
?printf("%s/n", _Strev(s));
?printf("%s/n", Strrev_WithoutRecursion(s));