STL算法设计理念 - 谓词，一元谓词demo

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

template <typename T>
class IsDiv
{
public:
IsDiv(const T d)
{
divisor = d;
}
bool operator()(T &t) // 一元谓词
{
return (t % divisor == 0);
}
protected:
private:
T divisor;
};

void play01()
{
vector<int> v;
for (int i = 10; i < 25; ++i) {
v.push_back(i);
}

int a = 4;
IsDiv<int> isDiv(a);

find_if(v.begin(), v.end(), isDiv);
//find_if(v.begin(), v.end(), IsDiv<int>(4)); // 也可以这样写
/* find_if()函数原型
template<class _InIt,
class _Pr> inline
_InIt find_if(_InIt _First, _InIt _Last, _Pr _Pred)
{	// find first satisfying _Pred
_DEBUG_RANGE(_First, _Last);
_DEBUG_POINTER(_Pred);
return (_Rechecked(_First,
_Find_if(_Unchecked(_First), _Unchecked(_Last), _Pred)));
}
*/
// find_if的返回值值一个迭代器

vector<int>::iterator it = find_if(v.begin(), v.end(), isDiv);
if (it == v.end()) {
cout << "fail\n";
}
else {
cout << "success " << *it << endl;
}
}

int main()
{
play01();

return 0;
}