shared_ptr

Common interface

use_count() : Get reference count number .

get() : Get the original pointer .

reset() : point NULL Memory .

matters needing attention

1. Cannot assign values directly NULL, Compilation failed ; If you need to empty it reset();reset after ,ptr point NULL Memory .

2. Memory cannot be released manually , as delete ptr.get(), This will cause a memory error , As for why , It's not clear .

3. Allocate memory first , Then give it to the smart pointer , No more release , as
    int * c = new int;
    boost::shared_ptr<int> pObj(c);
    delete c;

    A memory error will occur ,boost How to prevent users from being outside delete c What about ?

weak_ptr

Is a smart pointer to execute a weak reference . When you need it, you can use a strong ( share ) The pointer points to it ( When the object is released , It is empty ), Of course, this strong pointer should be released immediately after use

struct CBetterChild : public CSample { weak_ptr<CDad> myDad; void BringBeer()
{ shared_ptr<CDad> strongDad = myDad.lock(); // request a strong pointer if
(strongDad) // is the object still alive? strongDad->SetBeer(); // strongDad is
released when it goes out of scope. // the object retains the weak pointer } };
matters needing attention

1. Weak references if you need to manipulate class objects , Need to be converted to a strong reference , adopt lock Interface acquisition

2. After obtaining a strong reference , It is necessary to detect whether the object is empty , Because it is possible that the object has been released

3. After operation , Strong references should be released immediately , In other words, strong references are best temporary local variables

Common interface

lock() : Turn to strong reference , If the object has been released , Returns a null strong reference

expired(): Determine whether the object has been released

Technology
©2019-2020 Toolsou All rights reserved,
SQL Server Database Glossary CSS Animation effect dedecms Website is hacked How to solve hijacking to other websites Count the number of letters (java Language implementation )Java Basics ( Three ) String In depth analysis The difference between static method and non static method And storage location Django Personal blog building tutorial --- Time classified archiving Keras Save and load model (JSON+HDF5)hive Summary of processing methods for a large number of small files Website mobile phone number capture method