<thread>

public member function
<thread>

std::thread::joinable

bool joinable() const noexcept;
Check if joinable
Returns whether the thread object is joinable.

A thread object is joinable if it represents a thread of execution.

A thread object is not joinable in any of these cases:

Parameters

none

Return value

true if the thread is joinable.
false otherwise.

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
// example for thread::joinable
#include <iostream>       // std::cout
#include <thread>         // std::thread
 
void mythread() 
{
  // do stuff...
}
 
int main() 
{
  std::thread foo;
  std::thread bar(mythread);

  std::cout << "Joinable after construction:\n" << std::boolalpha;
  std::cout << "foo: " << foo.joinable() << '\n';
  std::cout << "bar: " << bar.joinable() << '\n';

  if (foo.joinable()) foo.join();
  if (bar.joinable()) bar.join();

  std::cout << "Joinable after joining:\n" << std::boolalpha;
  std::cout << "foo: " << foo.joinable() << '\n';
  std::cout << "bar: " << bar.joinable() << '\n';

  return 0;
}

Output (after 3 seconds):
Joinable after construction:
foo: false
bar: true
Joinable after joining:
foo: false
bar: false


Data races

The object is accessed.

Exception safety

No-throw guarantee: never throws exceptions.

See also