字符串倒序

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));