#include <iostream>
#include <string>
#include <set>
#include <sstream>
using namespace std;
set<string> dict; // string 集合
int main() {
string s, buf;
while (cin >> s) {
for (int i = 0; i < s.length(); ++i) {
if (isalpha(s[i]))
s[i] = tolower(s[i]);
else
s[i] = ' ';
}
stringstream ss(s);
while (ss >> buf)
dict.insert(buf);
}
for (set<string>::iterator it = dict.begin(); it != dict.end(); ++it)
cout << *it << "\n";
return 0;
}
set中元素已从小到大进行排序了
set<string>::iterator it是迭代器，用法与指针类似
