Solving bosses, why test01 did not use when creating a variable p constructor, destructor to tempora-CodePudding

why test01 did not use when creating a variable p constructor, destructor to temporary object, I think test01 like test02 use destructors should be just right,
# include
using namespace std;

The class Person
{
Int m_age;

Public:
The Person (s)
{
Cout & lt; <"The default structure & lt;" }
The Person (int the age) : m_age (age)
{
Cout & lt; <"And construct" & lt; }
The Person (const Person & amp; P)
{
M_age=p. _age;
Cout & lt; <"Copy constructor" & lt; }
To the Person (s)
{
Cout & lt; <"Destructor structure & lt;" }
};

The Person dowork ()
{
The Person p1;
Return p1;
}

Void test01 ()
{
Person p=dowork ();

}
Void test02 ()
{
Person p;
P=dowork ();
}

Int main ()
{
Cout & lt; <"Test01:" & lt; test01();
Cout & lt; <"Test02:" & lt; test02();
system("pause");
return 0;
}

CodePudding user response:

But the test USES only two destructor, it should be a local variable p1 destructor, temporary objects destructor, and variable p destructor should have three times as much as test02

CodePudding user response:

Brother you figured it out and reply to me, I also want to know why? Thank you for the

CodePudding user response:

For the Person p=dowork (); Compiler don't think this is an assignment statement, you first create p objects, but only for the distribution of p storage space, so you don't call the Person's constructor,
For the Person p; P=dowork (); , in the absence of any optimization, the compiler thinks this is the two statements, the first Person to call the constructor to create objects p, then call p=dowork () to the original content covers p, if switch on optimization, the compiler may be to combine the two statements into one, but that I am not sure,

CodePudding user response:

Baidu replication to eliminate