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std::shared_ptr::operator bool

STD：：共享[医]PTR：：操作员bool

explicit operator bool() const;​​

检查*this存储非空指针，即是否为get() != nullptr...

参数

%280%29

返回值

true如果*this存储一个指针，false否则。

例外

noexcept规格：

noexcept

注记

空共享[医]PTR%28use_count() == 0%5月29日存储一个非空指针。get()，例如，如果它是使用别名构造函数创建的。

例

二次

#include <iostream>
#include <memory>
 
typedef std::shared_ptr<int> IntPtr;
 
void report(IntPtr ptr) 
{
    if (ptr) {
        std::cout << "*ptr=" << *ptr << "\n";
    } else {
        std::cout << "ptr is not a valid pointer.\n";
    }
}
 
int main()
{
    IntPtr ptr;
    report(ptr
 
    ptr = IntPtr(new int(7)
    report(ptr
}

二次

产出：

二次

ptr is not a valid pointer.
*ptr=7

二次

另见

getreturns the stored pointer (public member function)

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在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。

http：//en.cppreference.com/w/cpp/Memory/Shared[医]PTR/算子[医]布尔

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