对于ios7扫描二维码功能的实现

class Solution {
public:
    void reverseWords(string &s) 
	{
		if(s.empty())
			return;
		int count = 0;
		int index = 0, indexTemp = 0, begin = 0, end = s.length()-1;
		while(s[begin] == ' ' && begin<s.length()-1)
			begin++;
		while(s[end] == ' ' && end>0)
			end--;
		if(end == 0 && s[end] == ' ')
		{
			s = "";
			return;
		}
		else if(end == 0)
		{
			s = s.substr(0,1);
			return;
		}
		index = begin;
		while(index <= end)
		{
			if(s[index] == ' ')
			{
				count++;
				while(s[index] == ' ')
					index++;
			}
			count++;
			index++;
		}
		string temp(count,'\0');
		index = end;
		indexTemp = 0;
		while(index >= begin)
		{
			if(s[index] == ' ')
			{
				temp[indexTemp] = s[index];
				while(s[index] == ' ')
					index--;
				indexTemp++;
			}
			temp[indexTemp] = s[index];
			indexTemp++;
			index--;
		}
		indexTemp = 0;
		begin = -1;
		end = -1;
		while(indexTemp < count)
		{
			if(temp[indexTemp] != ' ' && begin == -1)
			{
				begin = 0;
			}
			else if(indexTemp-1 >= 0 && temp[indexTemp-1] == ' '&&temp[indexTemp] != ' ')
			{
				begin = indexTemp;
			}
			else if((indexTemp+1 < count && temp[indexTemp+1] == ' ' && temp[indexTemp] != ' ') || ((indexTemp == count-1)&&temp[indexTemp] != ' '))
			{
				end = indexTemp;
				reverse(temp, begin, end);

			}
			indexTemp++;
		}
		s = temp;
    }
	
	void reverse(string &s, int begin, int end)
	{
		while(begin < end)
		{
			char temp = s[begin];
			s[begin] = s[end];
			s[end] = temp;
			begin++;
			end--;
		}
	}
};