C++ 递归和非递归实现字符串反转 char *reverse(char *s)

#include <iostream>
#include <string>
#include <sstream>
#include <assert.h>
using namespace std;
char *reverse(char *s)
{
  assert(s!=NULL);
  static stringstream ss;
  if (*s!='\0') reverse(s+1);
  ss<<*(s-1);
  return (char*)ss.str().c_str();
}
char *strReverse(char *s)   
{
  assert(s!=NULL);
    char *t=s;
    while(*t) *t++;
    for(int i=0;i<(t-s)/2;i++){
        *t=*(s+i);
        *(s+i)=*(s+(t-s)-i-1);  //(t-s)指针减法，括号不能省
        *(s+(t-s)-i-1)=*t;
    }
    *(s+(t-s))='\0';
    return s;
}
int main(void)
{
  string s = "123456789";
  char *p = (char*)s.data();
  p=strReverse(p);
  cout<<p<<endl;
  cout<<reverse(p)<<endl;
  return 0;
}
/*
测试结果：
987654321
123456789
--------------------------------
Process exited after 0.5639 seconds with return value 0
请按任意键继续. . .
*/

#include <iostream>
#include <cstring>
void reverse2(char *s,int n)
{
  if (n>1){
    char p=*s;
    *s=*(s+n-1);
    *(s+n-1)=p;
    reverse2(s+1,n-2);
  }
}
int main()
{
  char s[]="123456789";
  reverse2(s,strlen(s));  
  std::cout<<s<<std::endl;
  char *str;
  std::string t="hello,world!";
  str=(char*)t.c_str();
  reverse2(str,strlen(str));
  std::cout<<str<<std::endl;
  return 0;
}
/*
运行结果： 
987654321
!dlrow,olleh
--------------------------------
Process exited after 0.6639 seconds with return value 0
请按任意键继续. . .
*/