std::ptr_fun

 

C++

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Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)

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initializer_list (C++11)

bitset

hash (C++11)

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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

Optional and any

optional (C++17)

any (C++17)

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pair

tuple (C++11)

apply (C++17)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

integer_sequence (C++14)

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swap

exchange (C++14)

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

Type operations

declval (C++11)

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Function objects

Function wrappers
function (C++11)
mem_fn (C++11)
bad_function_call (C++11)
invoke (C++17)
Bind
bind (C++11)
is_bind_expression (C++11)
is_placeholder (C++11)
_1, _2, _3, ... (C++11)
Reference wrappers
reference_wrapper (C++11)
refcref (C++11)(C++11)
Operator wrappers
plus minus negate multiplies divides modulus logical_and logical_or logical_not	equal_to not_equal_to greater less greater_equal less_equal bit_and bit_or bit_xor bit_not (C++14)
Negators
not_fn not1 (deprecated) not2 (deprecated)	unary_negate (deprecated) binary_negate (deprecated)
Searchers
default_searcher (C++17) boyer_moore_searcher (C++17) boyer_moore_horspool_searcher (C++17)	make_default_searcher (C++17) make_boyer_moore_searcher (C++17) make_boyer_moore_horspool_searcher (C++17)
Old binders and adaptors
unary_function (until C++17)
binary_function (until C++17)
ptr_fun (until C++17)
pointer_to_unary_function (until C++17)
pointer_to_binary_function (until C++17)
mem_fun (until C++17)
mem_fun_tmem_fun1_tconst_mem_fun_tconst_mem_fun1_t (until C++17)(until C++17)(until C++17)(until C++17)
mem_fun_ref (until C++17)
mem_fun_ref_tmem_fun1_ref_tconst_mem_fun_ref_tconst_mem_fun1_ref_t (until C++17)(until C++17)(until C++17)(until C++17)
binder1stbinder2nd (until C++17)(until C++17)
bind1stbind2nd (until C++17)(until C++17)

 

Defined in header <functional>
template< class Arg, class Result > std::pointer_to_unary_function<Arg,Result>     ptr_fun( Result (*f)(Arg) );	(1)	(until C++17) (deprecated since C++11)
template< class Arg1, class Arg2, class Result > std::pointer_to_binary_function<Arg1,Arg2,Result>     ptr_fun( Result (*f)(Arg1, Arg2) );	(2)	(until C++17) (deprecated since C++11)

Creates a function wrapper object (either std::pointer_to_unary_function or std::pointer_to_binary_function), deducing the target type from the template arguments.

1) Effectively calls std::pointer_to_unary_function<Arg,Result>(f).

2) Effectively calls std::pointer_to_binary_function<Arg1,Arg2,Result>(f).

This function and the related types are deprecated as of C++11 in favor of the more general std::function and std::ref, both of which create callable adapter-compatible function objects from plain functions.

Parameters

f

-

pointer to a function to create a wrapper for

Return value

A function object wrapping f.

Exceptions

(none)

Example

Run this code

#include <string>
#include <iostream>
#include <algorithm>
#include <functional>
 
bool isvowel(char c)
{
    return std::string("aeoiuAEIOU").find(c) != std::string::npos;
}
 
int main()
{
    std::string s = "Hello, world!";
    std::copy_if(s.begin(), s.end(), std::ostreambuf_iterator<char>(std::cout),
                 std::not1(std::ptr_fun(isvowel)));
// C++11 alternatives: 
//               std::not1(std::cref(isvowel)));
//               std::not1(std::function<bool(char)>(isvowel)));
 
}

Output:

Hll, wrld!