std::shared_ptr<T>::operator bool
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explicit operator bool() const noexcept; |
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*this get() != nullptr
()
*this true false
(use_count() == 0) shared_ptr get() shared_ptr
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);
}
:
ptr is not a valid pointer.
*ptr=7
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