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std::shared_ptr<T>::operator bool

From cppreference.com
 
 
Memory management library
Allocators
Memory resources
Uninitialized storage (until C++20*)
Garbage collector support (until C++23)
 
 
explicit operator bool() const noexcept;
(constexpr since C++26)

Checks if *this stores a non-null pointer.

Return value

get() != nullptr

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

#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

See also

returns the stored pointer
(public member function) [edit]