string类 方法

可以进行string对象或和c风格字符串之间'<' '>' '==' '!='比较
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size()   length() 返回字符串长度
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find()
//*pos都表示 从字符串pos个字符开始查找*//
1>find(const string & str,size_type pos=0)
返回str字符串首次出现索引　否则返回string::npos

2>find(const char　*s,size_type pos=0)
返回字符串s首次出现索引　否则返回string::npos

3>find(const char　*s,size_type pos=0,size_type n)
返回字符串s前n个字符首次出现索引　否则返回string::npos

4>find(char ch,size_type pos=0) const
返回字符ch首次出现索引　否则返回string::npos

 

rfind("str")
查找字符或字符串最后一次出现的位子返回索引

find_first_of("str")
返回字符串中查找首个在参数中的字符的位子

find_last_of("str")
返回字符串中查找最后个在参数中的字符的位子

find_first_not_of("str")
返回在字符串中查找首个不在参数中的字符的位子

find_first_not_of("str")
返回在字符串中查找最后一个不在参数中的字符的位子

 

 

 

//
做个判断
while(判断)
{
  　……
　  判断　以便判断是否循环
}

******************************************************************
读入
while(读入是否成功或是否达到结束要求)
{
  　……
　  读入　
}

//////////////////////////////////////////////////////
//
//guessword.cpp
//
/////////////////////////////////////////////////////
#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
#include <cctype>
using std::string;
const int NUM = 26;
const string wordlist[NUM] = {"apiary", "beetle", "cereal",
    "danger", "ensign", "florid", "garage", "health", "insult",
    "jackal", "keeper", "loaner", "manage", "nonce", "onset",
    "plaid", "quilt", "remote", "stolid", "train", "useful",
    "valid", "whence", "xenon", "yearn", "zippy"};

int main()
{
    using namespace std;
   
    srand(time(0));
    char play;
    cout << "Will you play a word game? <y/n> ";
    cin >> play;
    play = tolower(play);
    while (play == 'y')
    {
        string target = wordlist[rand() % NUM];
        int length = target.length();
        string attempt(length, '-');
        string badchars;
        int guesses = 6;
        cout << "Guess my secret word. It has " << length
            << " letters, and you guess\n"
            << "one letter at a time. You get " << guesses
            << " wrong guesses.\n";
        cout << "Your word: " << attempt << endl;
        while (guesses > 0 && attempt != target)
        {
            char letter;
            cout << "Guess a letter: ";
            cin >> letter;
            if (badchars.find(letter) != string::npos
                || attempt.find(letter) != string::npos)
            {
                cout << "You already guessed that. Try again.\n";
    continue;
            }
            int loc = target.find(letter);
            if (loc == string::npos)
            {
                cout << "Oh, bad guess!\n";
                --guesses;
                badchars += letter; // add to string
            }
            else
            {
                cout << "Good guess!\n";
                attempt[loc]=letter;
                // check if letter appears again
                loc = target.find(letter, loc + 1);
                while (loc != string::npos)
                {
                    attempt[loc]=letter;
                    loc = target.find(letter, loc + 1);
                }
   }
            cout << "Your word: " << attempt << endl;
            if (attempt != target)
            {
                if (badchars.length() > 0)
                    cout << "Bad choices: " << badchars << endl;
                cout << guesses << " bad guesses left\n";
            }
        }
        if (guesses > 0)
            cout << "That's right!\n";
        else
            cout << "Sorry, the word is " << target << ".\n";
  
        cout << "Will you play another? <y/n> ";
        cin >> play;
        play = tolower(play);
    }
 
    cout << "Bye\n";
 
    return 0;
}