判断字符串是否回文

在很久以前自己写过一段关于回文的，近来学了下STL感觉用起来更好，就贴出来看看。#include<iostream>//#include<malloc.h>using namespace std;void huiwen(char str[]){int i=0,j;j=strlen(str)-1;//sizeof(str[0]);cout<<strlen(str)<<endl;bool sign=true;while(sign)//当i>=j时说明他们的对称为相等从而退出循环{sign=i<j;if(str[i]!=str[j])break;else{i++;j--;}}if(sign){cout<<"str不是回文序"<<endl;}else{ cout<<"str是回文序列"<<endl;}}void main(){char str[]="123454321";huiwen(str);}

下面是用STL Vector实现的

#include<iostream>//#include<string>#include<vector>#include<algorithm>using namespace std;//void ishuwen(const string & strm);int main(){//string strm("12345321");//ishuwen(strm);vector<char> coll1;vector<char> coll2;char str[]="abcdefgfedcba";//以下这样做可以达到要求，但必须确保最后的/0结束符有位置//最好不要这样//char str[12];//cin>>str;//以下这样是错误的字符不允许这样做//char *str;//cin>>str;int num=sizeof(str)/sizeof(str[0]);cout<<"the str's size:"<<num<<endl;copy(str,str+num-1,back_inserter(coll1));//由于字符数组加了"/0"字符所以减一vector<char>::iterator pos1,pos2;for(pos1=coll1.begin();pos1!=coll1.end();++pos1){cout<<*pos1<<" ";}cout<<endl;copy(coll1.rbegin(),coll1.rend(),back_inserter(coll2)); for(pos2=coll2.begin();pos2!=coll2.end();++pos2){cout<<*pos2<<" ";}cout<<endl;//用算法进行判断if(equal(coll1.begin(),coll1.end(),coll2.begin())){cout<<"the str is a huwen"<<endl;}else{cout<<"the str is not a huwen"<<endl;}}

下面是用String实现的

#include<iostream>#include<string>//#include<vector>#include<algorithm>using namespace std;int main(){string s1,s2;cout<<"please input the str s1:"<<endl;getline(cin,s1);cout<<"the str s1:"<<s1<<endl;int num;num=s1.size();cout<<"the str's size():"<<num<<endl; //copy(s1.rbegin(),s1.rend(),//s2(s1);//transform(s1.rbegin(),s1.rend(),back_inserter(s2));一般此函数有5个参数//copy(s1.rbegin(),s1.rend(),back_inserter(s2));//s2.assign(s1.rbegin(),s1.rend());//此处运用了string的迭代器操作函数s2.append(s1.rbegin(),s1.rend());//此处亦是String的迭代器操作函数cout<<"the str s2:"<<s2<<endl;int x=s1.compare(s2);//调用string的比较操作函数返回0即相等，1为小于，-1为大于相当于equal()函数功能判断相等if(x==0){cout<<"the str s1==s2,so the str is huwen!"<<endl;}else{cout<<"the str is not huwen!"<<endl;}}