【转】string类使用示例(源代码)

http://blog.sina.com.cn/s/blog_51409e8f01009h7k.html~type=v5_one&label=rela_nextarticle

1)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s("hehe");
    cout<<s<<endl;
    cin.get();
}
2)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    char chs[] = "hehe";
    string s(chs);
    cout<<s<<endl;
    cin.get();
}
3)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    char chs[] = "hehe";
    string s(chs,1,3);    //指定从chs的索引1开始,最后复制3个字节
    cout<<s<<endl;
    cin.get();
}
4)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s1("hehe");
    string s2(s1);   
    cout<<s2<<endl;
    cin.get();
}
5)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s1("hehe",2,3);
    string s2(s1);   
    cout<<s2<<endl;
    cin.get();
}
6)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    char chs[] = "hehe";
    string s(chs,3);    //将chs前3个字符作为初值构造
    cout<<s<<endl;
    cin.get();
}
7)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s(10,'k');    //分配10个字符,初值都是'k'
    cout<<s<<endl;
    cin.get();
}
//以上是string类实例的构造手段,都很简单.

9)
//赋新值
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s(10,'k');    //分配10个字符,初值都是'k'
    cout<<s<<endl;
    s = "hehehehe";
    cout<<s<<endl;
    s.assign("kdje");
    cout<<s<<endl;
    s.assign("fkdhfkdfd",5);    //重新分配指定字符串的前5的元素内容
    cout<<s<<endl;       
    cin.get();
}
10)
//swap方法交换
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s1 = "hehe";
    string s2 = "gagaga";
    cout<<"s1 : "<<s1<<endl;
    cout<<"s2 : "<<s2<<endl;
    s1.swap(s2);
    cout<<"s1 : "<<s1<<endl;
    cout<<"s2 : "<<s2<<endl;
    cin.get();
}
11)
//+=,append(),push_back()在尾部添加字符
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "hehe";
    s += "gaga";
    cout<<s<<endl;
    s.append("嘿嘿");    //append()方法可以添加字符串
    cout<<s<<endl;
    s.push_back('k');    //push_back()方法只能添加一个字符...
    cout<<s<<endl;
    cin.get();
}
12)
//insert() 插入字符.其实,insert运用好,与其他的插入操作是一样的.
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "hehe";
    s.insert(0,"头部");            //在头部插入
    s.insert(s.size(),"尾部");    //在尾部插入
    s.insert(s.size()/2,"中间");//在中间插入
    cout<<s<<endl;
    cin.get();
}
13)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg";
    s.erase(0,1);    //从索引0到索引1,即删除掉了'a'
    cout<<s<<endl;
    //其实,还可以使用replace方法来执行删除操作
    s.replace(2,3,"");//即将指定范围内的字符替换成"",即变相删除了
    cout<<s<<endl;
    cin.get();
}

14)
//clear() 删除全部字符
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg";
    cout<<s.length()<<endl;
    s.clear();
    cout<<s.length()<<endl;
    //使用earse方法变相全删除
    s = "dkjfd";
    cout<<s.length()<<endl;
    s.erase(0,s.length());
    cout<<s.length()<<endl;

    cin.get();
}
15)
//replace() 替换字符
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg";
    s.replace(2,3,"!!!!!");//从索引2开始3个字节的字符全替换成"!!!!!"
    cout<<s<<endl;
    cin.get();
}
16)
//==,!=,<,<=,>,>=,compare()  比较字符串
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s1 = "abcdefg";
    string s2 = "abcdefg";   
    if (s1==s2)cout<<"s1 == s2"<<endl;
    else cout<<"s1 != s2"<<endl;
   
    if (s1!=s2)cout<<"s1 != s2"<<endl;
    else cout<<"s1 == s2"<<endl;
   
    if (s1>s2)cout<<"s1 > s2"<<endl;
    else cout<<"s1 <= s2"<<endl;
   
    if (s1<=s2)cout<<"s1 <= s2"<<endl;
    else cout<<"s1 > s2"<<endl;

    cin.get();
}
17)
//size(),length()  返回字符数量
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg";
    cout<<s.size()<<endl;
    cout<<s.length()<<endl;

    cin.get();
}
18)
//max_size() 返回字符的可能最大个数
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg";
    cout<<s.max_size()<<endl;

    cin.get();
}
19)
//empty()  判断字符串是否为空
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s ;
    if (s.empty())
        cout<<"s 为空."<<endl;
    else
        cout<<"s 不为空."<<endl;

    s = s + "abcdefg";
    if (s.empty())
        cout<<"s 为空."<<endl;
    else
        cout<<"s 不为空."<<endl;

    cin.get();
}
20)
// [ ], at() 存取单一字符
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg1111";
   
    cout<<"use []:"<<endl;
    for(int i=0; i<s.length(); i++)
    {
        cout<<s[i]<<endl;
    }
    cout<<endl;

    cout<<"use at():"<<endl;
    for(int i=0; i<s.length(); i++)
    {
        cout<<s.at(i)<<endl;
    }
    cout<<endl;
   
    cin.get();
}
21)
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg1111";
   
    const char * chs1 = s.c_str();
    const char * chs2 = s.data();

    cout<<"use at():"<<endl;
    int i;
    for(i=0; i<s.length(); i++)
    {
        cout<<"c_str() : "<<chs1[i]<<endl;
        cout<<"data() : "<<chs2[i]<<endl;
    }
    cout<<"c_str() : "<<chs1<<endl;
    cout<<"data() : "<<chs2<<endl;
    cout<<endl;
   
    cin.get();
}
22)
// substr() 返回某个子字符串
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg1111";
   
    string str = s.substr(5,3);//从索引5开始3个字节
    cout<<str<<endl;
   
    cin.get();
}
23)
// find 查找函数
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg1111";
    string pattern = "fg";
    string::size_type pos;
    pos = s.find(pattern,0);        //从索引0开始,查找符合字符串"f"的头索引
    cout<<pos<<endl;
    string str = s.substr(pos,pattern.size());
    cout<<str<<endl;
    cin.get();
}
24)
// begin() end() 提供类似STL的迭代器支持
#include <string>
#include <iostream>
using namespace std;

void main()
{
    string s = "abcdefg1111";
    for(string::iterator iter = s.begin(); iter!=s.end(); iter++)
    {
        cout<<*iter<<endl;
    }
    cout<<endl;

    cin.get();
}