std::shared_ptr<T>::operatorbool (3) - Linux Manuals

std::shared_ptr<T>::operatorbool: std::shared_ptr<T>::operatorbool

NAME

std::shared_ptr<T>::operatorbool - std::shared_ptr<T>::operatorbool

Synopsis

explicit operator bool() const noexcept;

Checks if *this stores a non-null pointer, i.e. whether get() != nullptr.

Parameters

(none)

Return value

true if *this stores a pointer, false otherwise.

Notes

An empty shared_ptr (where use_count() == 0) may store a non-null pointer accessible by get(), e.g. if it were created using the aliasing constructor.

Example

// Run this code

  #include <iostream>
  #include <memory>

  void report(std::shared_ptr<int> ptr)
  {
      if (ptr) {
          std::cout << "*ptr=" << *ptr << "\n";
      } else {
          std::cout << "ptr is not a valid pointer.\n";
      }
  }

  int main()
  {
      std::shared_ptr<int> ptr;
      report(ptr);

      ptr = std::make_shared<int>(7);
      report(ptr);
  }

Output:

  ptr is not a valid pointer.
  *ptr=7