string中常用的函数

发现在string在处理这符串是很好用,就找了一篇文章放在这里了..

用 string来代替char * 数组，使用sort排序算法来排序，用unique 函数来去重
1、Define
           string s1 = "hello";
           string s2 = "world";
           string s3 = s1 + "," + s2 +"!\n";
2、append
           s1 += ",shanshan\n";
3、Compare
           if(s1 == s2)
              .....
           else if(s1 == "hello")
              .....
4、 string 重载了许多操作符，包括 +, +=, <, =, , [], <<, >>等，正式这些操作符，对字符串操作非常方便

#include <string>#include <iostream>using namespace std;int main(){           string strinfo="Please input your name:";           cout << strinfo ;           cin >> strinfo;        if( strinfo == "winter" )           cout << "you are winter!"<<endl;        else if( strinfo != "wende" )           cout << "you are not wende!"<<endl;        else if( strinfo < "winter")           cout << "your name should be ahead of winter"<<endl;        else            cout << "your name should be after of winter"<<endl;           strinfo += " , Welcome to China!";           cout << strinfo<<endl;           cout <<"Your name is :"<<endl;           string strtmp = "How are you? " + strinfo;        for(int i = 0 ; i < strtmp.size(); i ++)           cout<<strtmp[i];        return 0;} 

5、find函数
由于查找是使用最为频繁的功能之一，string 提供了非常丰富的查找函数。其列表如下：

以上函数都是被重载了4次，以下是以find_first_of 函数为例说明他们的参数，其他函数和其参数一样，也就是说总共有24个函数：

size_type find_first_of(const basic_string& s, size_type pos = 0)size_type find_first_of(const charT* s, size_type pos, size_type n)size_type find_first_of(const charT* s, size_type pos = 0)size_type find_first_of(charT c, size_type pos = 0)

所有的查找函数都返回一个size_type类型，这个返回值一般都是所找到字符串的位置，如果没有找到，则返回string::npos。其实string::npos表示的是-1。即没找到就返回-1。例子如下：#include <string>#include <iostream>using namespace std;int main(){           string strinfo="      //*---Hello Word!......------";           string strset="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";        int first = strinfo.find_first_of(strset);        if(first == string::npos) {                    cout<<"not find any characters"<<endl;                return -1;           }         int last = strinfo.find_last_of(strset);        if(last == string::npos) {                    cout<<"not find any characters"<<endl;                return -1;           }            cout << strinfo.substr(first, last - first + 1)<<endl;//string.substr是子串        return 0;}6、insert函数, replace函数和erase函数

string只是提供了按照位置和区间的replace函数，而不能用一个string字串来替换指定string中的另一个字串。例子：#include <string>#include <iostream>using namespace std;int main() {           string strinfo="This is Winter, Winter is a programmer. Do you know Winter?";           cout<<"Orign string is :\n"<<strinfo<<endl;           string_replace(strinfo, "Winter", "wende");           cout<<"After replace Winter with wende, the string is :\n"<<strinfo<<endl;        return 0;}

string.erase(pos,srclen);//srclen是删除的长度string.insert(pos,strdst); //pos是定位，strdst是插入的函数void string_replace(string & strBig, const string & strsrc, const string &strdst) {           string::size_type pos=0;           string::size_type srclen=strsrc.size();           string::size_type dstlen=strdst.size();        while( (pos=strBig.find(strsrc, pos)) != string::npos){                   strBig.erase(pos, srclen);                   strBig.insert(pos, strdst);                   pos += dstlen;           }}