UVA10815 安迪的第一个字典 Andy‘s First Dictionary

Adventures in Disneyland
Two blondes were going to Disneyland when they came to a fork in the
road. The sign read: "Disneyland Left."
So they went home.

a
adventures
blondes
came
disneyland
fork
going
home
in
left
read
road
sign
so
the
they
to
two
went
were
when

#include<iostream>
#include<algorithm>
#include<sstream>
#include<string>
#include<set>//因为可能有重复的单词，而set可以去重，使用起来更好。
using namespace std;
string str,str2;
stringstream ss;
set<string> jh;
int main() {
  while (cin >> str ) {
    for (int i = 0; i < str.length(); i++) {//去除非单词字符
      if (isalpha(str[i])) {
        str[i] = tolower(str[i]);
      }
      else {
        str[i] = ' ';
      }
    }
    ss << str; //每次得清空ss
    //stringstream ss(str);  如果这样写就不用每次清空ss了.
    while (ss >> str) 
      jh.insert(str);
    ss.clear();//这里必须清空...具体原因为止.
  }
  for (set<string>::iterator it = jh.begin(); it != jh.end(); it++) {
    cout << *it << endl;
  }
  return 0;
}