Timus 1601. AntiCAPS 修正大写句子

The blonde Angela has a new whim: internet chats. Of course, as any blonde, she writes her messages using the upper case. You are the moderator of Angela‘s favorite chat and you‘re fed up with her upper-case
messages. The problem is that Angela does not respond to your warnings. You decided to write a simple antiCAPS corrector, which would make Angela‘s messages readable.

The correction rules are very simple:

1. Sentences in a message consist of words, spaces and punctuation marks.
2. Words consist of English letters.
3. Sentences end with a full stop, exclamation mark, or question mark.
4. The first word of each sentence must start with a capital letter, and all other letters of the sentence must be lowercase.

Input

You are given Angela‘s message, which consists of uppercase English letters, spaces, line breaks and punctuation marks: full stops, commas, dashes, colons, exclamation and question marks. Total length
of message is not exceeding 10000 symbols.

Output

Output the corrected message.

Sample

HI THERE!
HOW DID YOU KNOW I AM A BLONDE?

Hi there!
How did you know i am a blonde?

就是修正个全是大写的句子。

这里注意一点(as in codes‘ comment)：

keep the state, because blonde would do anything, and put the comma, in one line, and start typing another line.

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

void toLowerCase(string &s, bool &senBegin)
{
	for (unsigned i = 0; i < s.size(); i++)
	{
		if (‘ ‘ == s[i]) continue;
		if (senBegin)
		{
			if (‘A‘ <= s[i] && s[i] <= ‘Z‘ || ‘a‘ <= s[i] && s[i] <= ‘z‘)
			{
				s[i] = toupper(s[i]);
				senBegin = false;
			}
			continue;
		}
		if (‘.‘ == s[i] || ‘?‘ == s[i] || ‘!‘ == s[i]) senBegin = true;
		s[i] = tolower(s[i]);
	}
}

int AntiCAPS1601()
{
	string s;
	bool senBegin = true;//keep the state, because blonde would do anything, and put the comma, in one line, and start typing another line.
	while (getline(cin, s))
	{
		toLowerCase(s, senBegin);
		cout<<s<<endl;
	}
	return 0;
}