Defined in header <functional> | ||
|---|---|---|
template< class F, class T > std::binder1st<F> bind1st( const F& f, const T& x ); | (1) | (deprecated in C++11) (removed in C++17) |
template< class F, class T > std::binder2nd<F> bind2nd( const F& f, const T& x ); | (2) | (deprecated in C++11) (removed in C++17) |
Binds a given argument x to a first or second parameter of the given binary function object f. That is, stores x within the resulting wrapper, which, if called, passes x as the first or the second parameter of f.
f to x. Effectively calls std::binder1st<F>(f, typename F::first_argument_type(x)).f to x. Effectively calls std::binder2nd<F>(f, typename F::second_argument_type(x)).| f | - | pointer to a function to bind an argument to |
| x | - | argument to bind to f |
A function object wrapping f and x.
May throw implementation-defined exceptions.
#include <algorithm>
#include <cmath>
#include <cstddef>
#include <functional>
#include <iomanip>
#include <iostream>
#include <vector>
int main()
{
std::vector<double> a = {0, 30, 45, 60, 90, 180};
std::vector<double> r(a.size());
const double pi = std::acos(-1); // since C++20 use std::numbers::pi
std::transform(a.begin(), a.end(), r.begin(),
std::bind1st(std::multiplies<double>(), pi / 180.0));
// an equivalent lambda is: [pi](double a) { return a * pi / 180.0; });
for (std::size_t n = 0; n < a.size(); ++n)
std::cout << std::setw(3) << a[n] << "° = " << std::fixed << r[n]
<< " rad\n" << std::defaultfloat;
}Output:
0° = 0.000000 rad 30° = 0.523599 rad 45° = 0.785398 rad 60° = 1.047198 rad 90° = 1.570796 rad 180° = 3.141593 rad
|
(deprecated in C++11)(removed in C++17) | function object holding a binary function and one of its arguments (class template) |
|
(C++20)(C++23) | bind a variable number of arguments, in order, to a function object (function template) |
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