C++ Tutorial/STL Introduction/binary function
Версия от 14:21, 25 мая 2010; (обсуждение)
std::binary_function
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
using namespace std;
// include self-defined fopow<>
#include <functional>
#include <cmath>
template <class T1, class T2>
struct fopow : public std::binary_function<T1, T2, T1>
{
T1 operator() (T1 base, T2 exp) const {
return std::pow(base,exp);
}
};
int main()
{
vector<int> coll;
// insert elements from 1 to 9
for (int i=1; i<=9; ++i) {
coll.push_back(i);
}
// print 3 raised to the power of all elements
transform (coll.begin(), coll.end(), // source
ostream_iterator<float>(cout," "), // destination
bind1st(fopow<float,int>(),3)); // operation
cout << endl;
// print all elements raised to the power of 3
transform (coll.begin(), coll.end(), // source
ostream_iterator<float>(cout," "), // destination
bind2nd(fopow<float,int>(),3)); // operation
cout << endl;
}3 9 27 81 243 729 2187 6561 19683 1 8 27 64 125 216 343 512 729
