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Returns whether the object is callable.
A function object is callable if it is not an empty function (i.e., if it has a callable object as target).
Output:
Reference
C library:
- <cassert> (assert.h)
- <cctype> (ctype.h)
- <cerrno> (errno.h)
-
<cfenv> (fenv.h)C++11
- <cfloat> (float.h)
-
<cinttypes> (inttypes.h)C++11
- <ciso646> (iso646.h)
- <climits> (limits.h)
- <clocale> (locale.h)
- <cmath> (math.h)
- <csetjmp> (setjmp.h)
- <csignal> (signal.h)
- <cstdarg> (stdarg.h)
-
<cstdbool> (stdbool.h)C++11
- <cstddef> (stddef.h)
-
<cstdint> (stdint.h)C++11
- <cstdio> (stdio.h)
- <cstdlib> (stdlib.h)
- <cstring> (string.h)
-
<ctgmath> (tgmath.h)C++11
- <ctime> (time.h)
-
<cuchar> (uchar.h)C++11
- <cwchar> (wchar.h)
- <cwctype> (wctype.h)
Containers:
-
<array>C++11
- <deque>
-
<forward_list>C++11
- <list>
- <map>
- <queue>
- <set>
- <stack>
-
<unordered_map>C++11
-
<unordered_set>C++11
- <vector>
-
Input/Output:
Multi-threading:
-
<atomic>C++11
-
<condition_variable>C++11
-
<future>C++11
-
<mutex>C++11
-
<thread>C++11
-
Other:
- <algorithm>
- <bitset>
-
<chrono>C++11
-
<codecvt>C++11
- <complex>
- <exception>
- <functional>
-
<initializer_list>C++11
- <iterator>
- <limits>
- <locale>
- <memory>
- <new>
- <numeric>
-
<random>C++11
-
<ratio>C++11
-
<regex>C++11
- <stdexcept>
- <string>
-
<system_error>C++11
-
<tuple>C++11
-
<type_traits>C++11
-
<typeindex>C++11
- <typeinfo>
- <utility>
- <valarray>
<functional>
functions
wrapper classes
- binary_negate
-
functionC++11
-
reference_wrapperC++11
- unary_negate
operator classes
other classes
-
bad_function_callC++11
-
hashC++11
-
is_bind_expressionC++11
-
is_placeholderC++11
-
namespaces
-
placeholdersC++11
-
deprecated
function
-
function::~functionC++11
-
function::functionC++11
member functions
-
function::assignC++11
-
function::operator boolC++11
-
function::operator()C++11
-
function::operator=C++11
-
function::swapC++11
-
function::targetC++11
-
function::target_typeC++11
-
non-member overloads
-
relational operators (function)C++11
-
swap (function)C++11
-
- Reference
- <functional>
- function
- operator bool
public member function
<functional>
std::function::operator bool
explicit operator bool() const noexcept;
Check if callable
A function object is callable if it is not an empty function (i.e., if it has a callable object as target).
Parameters
noneReturn value
true if the object is callable.false otherwise (the object is an empty function).Example
|
|
Output:
foo is not callable. bar is callable. |
Data races
The object is accessed.Exception safety
No-throw guarantee: this member function never throws exceptions.See also
- function::target
- Get pointer to target (public member function)
- function::operator()
- Call target (public member function)
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© cplusplus.com, 2000-2025 - All rights reserved - v3.3.4s
Spotted an error? contact us