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This article shows you how to use constructors in C++. The content is concise and easy to understand. It will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

1. Constructor:

1. What is a constructor?

The simple understanding of this constructor is that in a class, there is a function whose name is the same as the class name, and the constructor does not return a value type (Test () this function is the constructor. ):

# include

Class Test:

{

Public:

Test ()

{

Printf ("Test ()\ n")

}

}

2. Call the constructor:

(1) in general, the constructor is called automatically when it is defined (the main function is to initialize the property in the class automatically, which is what we call a variable. And the automatic meaning here, that is, when you create an object, it will automatically call the constructor, you do not have to write the constructor in the main function. ):

# include

Class Test

{

Public:

Test ()

{

Printf ("Test ()\ n")

}

}

Int main ()

{

Test t; / / call Test ()

Return 0

}

The results of the demonstration are as follows:

Root@txp-virtual-machine:/home/txp/c++#. / a.out

Test ()

(2) in some special cases, you need to call the constructor manually (this will have a case study in the constructor with parameters below)

Second, the constructor with parameters

(1) the constructor can define parameters as needed.

Class Test

{

Public:

Test (int v)

{

}

}

(2) there can be multiple overloaded constructors in a class (what overloaded function, to put it simply, can be the same as the function name, but its passing parameter type or return type is different is the overloaded function. Let's take a look at a specific example of a parameter constructor:

# include

Class Test

{

Private:

Int m_value

Public:

Test ()

{

Printf ("Test ()\ n")

M_value = 0

}

Test (int v)

{

Printf ("Test (int v), v =% d\ n", v)

M_value = v

}

Int getValue ()

{

Return m_value

}

}

Int main ()

{

Test ta [3] = {Test (), Test (1), Test (2)}

For (int item0; I

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