std::bind1st, std::bind2nd
From cppreference.com
< cpp | utility | functional
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Utilities library
Type support (basic types, RTTI)
Library feature-test macros (C++20)
(C++11)
(C++20)
(C++26)
(C++20)
Coroutine support (C++20)
Contract support (C++26)
(C++20)(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)(C++20)(C++20)
(C++20)(C++20)(C++20)
General utilities
Relational operators (deprecated in C++20)
(C++20)(C++20)(C++20)
(C++20)(C++20)(C++20)
(C++20)
Swap and type operations
Common vocabulary types
Function objects
(C++11)
(C++23)
(C++26)
(C++26)
(C++11)
(C++11)
(C++20)(C++23)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)(C++11)
(C++20)(C++20)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++17)
(C++17)
(C++17)
(C++17)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)(until C++17*)(until C++17*)(until C++17*)
(until C++20*)
(until C++20*)
(until C++17*)(until C++17*)
bind1stbind2nd
(until C++17*)(until C++17*)
(until C++17*)
(until C++17*)(until C++17*)(until C++17*)(until C++17*)
(until C++20*)
(until C++20*)
Defined in header
<functional>
template< class F, class T >
std::binder1st <F> bind1st( const F& f, const T& x );
(1)
(deprecated in C++11) std::binder1st <F> bind1st( const F& f, const T& x );
(removed in C++17)
template< class F, class T >
std::binder2nd <F> bind2nd( const F& f, const T& x );
(2)
(deprecated in C++11) std::binder2nd <F> bind2nd( const F& f, const T& x );
(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.
1) Binds the first argument of f to x. Effectively calls std::binder1st <F>(f, typename F::first_argument_type(x)).
2) Binds the second argument of f to x. Effectively calls std::binder2nd <F>(f, typename F::second_argument_type(x)).
[edit] Parameters
f
-
pointer to a function to bind an argument to
x
-
argument to bind to f
[edit] Return value
A function object wrapping f and x.
[edit] Exceptions
May throw implementation-defined exceptions.
[edit] Example
Run this code
#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
[edit] See also
(deprecated in C++11)(removed in C++17)
(class template) [edit]
(C++20)(C++23)
(function template) [edit]