C++详细分析lambda表达式的本质

stable_sort(words.begin(), words.end(), 
		[](const string& s1, const string& s2) 
		{ return s1.size() < s2.size(); });
class ShorterString 
{
public:
	bool operator()(const string& s1,const string& s2)const
	{
		return s1.size() < s2.size();
	}
};
// 等价于
stable_sort(words.begin(), words.end(), ShorterString();
// 或者
ShorterString s;
stable_sort(words.begin(), words.end(), s;

auto wc = find_if(words.begin(), words.end(), 
    [sz] (const string& s) { return s.size() >= sz; } );
class Sizecomp
{
public:
	Sizecomp(size_t n) :sz(n) {}
	bool operator()(const string& s)const
	{
		return s.size() >= sz;
	}
private:
	size_t sz;
};
// 等价于
auto wc = find_if(words.begin(), words.end(), Sizecomp(sz));

class StrLenBetween
{
public:
	StrLenBetween(int m, int x) :min(m), max(x) {}
	bool operator()(const string& s)const
	{
		return s.size() >= min && s.size() <= max;
	}
private:
	int min;
	int max;
};
void readStr(istream& is, vector<string>& v)
{
	string s;
	while (is >> s)
		v.push_back(s);
}
int main()
{
	vector<string> vec;
	readStr(cin, vec);
	const int min = 1;
	const int max = 10;
	cout << "len 1~9 : " << count_if(vec.begin(), vec.end(), [min, max](const string& s)->bool {return s.size() >= 1 && s.size() <= 9; }) << endl;
	cout << "len >= 10 : " << count_if(vec.begin(), vec.end(), [max](const string& s)->bool {return s.size() >= max; }) << endl;
	cout << "len 1~9 : " << count_if(vec.begin(), vec.end(), StrLenBetween(min, max)) << endl;
	return 0;
}