Create a C ++ object Array

 

Use a one-dimensional pointer to create an object array:

 

// ================================================ ==============================================

// Name: main. cpp

// Author: ShiGuang

// Version:

// Copyright: sg131971@qq.com

// Description: Hello World in C ++, Ansi-style

// ================================================ ==============================================

 

# Include <iostream>

# Include <string>

Using namespace std;

 

Int nextStudentID = 1;

Class StudentID

{

Public:

StudentID ()

{

Cout <"StudentID ()" <endl;

Value = nextStudentID ++;

Cout <"value:" <value <endl;

}

~ StudentID ()

{

-- NextStudentID;

Cout <"~ StudentID () "<endl;

}

Protected:

Int value;

};

 

Class Student

{

Public:

Student (string pName = "noName ")

{

Cout <"Student ()" <endl;

Name = pName;

Cout <"name:" <name <endl;

}

~ Student ()

{

Cout <"~ Student () "<endl;

}

Protected:

String name;

StudentID id;

};

 

Int main (int argc, char ** argv)

{

Int I;

Cin> I;

Student * p = new Student [I];

Delete [] p;

Cout <"nextStudentID:" <nextStudentID <endl;

Return 0;

}

Result:

 

 

 

> 3

StudentID ()

Value: 1

Student ()

Name: noName

StudentID ()

Value: 2

Student ()

Name: noName

StudentID ()

Value: 3

Student ()

Name: noName

~ Student ()

~ StudentID ()

~ Student ()

~ StudentID ()

~ Student ()

~ StudentID ()

NextStudentID: 1

 

Use a two-dimensional pointer to create a dynamic array:

 

 

// ================================================ ==============================================

// Name: main. cpp

// Author: ShiGuang

// Version:

// Copyright: sg131971@qq.com

// Description: Hello World in C ++, Ansi-style

// ================================================ ==============================================

 

# Include <iostream>

# Include <string>

Using namespace std;

 

Int nextStudentID = 1;

Class StudentID

{

Public:

StudentID ()

{

Cout <"StudentID ()" <endl;

Value = nextStudentID ++;

Cout <"value:" <value <endl;

}

~ StudentID ()

{

-- NextStudentID;

Cout <"~ StudentID () "<endl;

}

Protected:

Int value;

};

 

Class Student

{

Public:

Student (string pName = "noName ")

{

Cout <"Student ()" <endl;

Name = pName;

Cout <"name:" <name <endl;

}

~ Student ()

{

Cout <"~ Student () "<endl;

}

Protected:

String name;

StudentID id;

};

 

Int main (int argc, char ** argv)

{

Int I, j;

String temp;

Cin> I;

Student ** p = new Student * [I];

For (j = 0; j <I; j ++)

{

Cout <"j:" <j <endl;

Cin> temp;

P [j] = new Student (temp );

Cout <"nextStudentID:" <nextStudentID <endl;

}

For (j = I-1; j> = 0; j --)

Delete p [j];

// Delete [] p; // This statement does not seem to work.

Cout <"nextStudentID:" <nextStudentID <endl;

Return 0;

}

Result:

 

> 3

J: 0

> Shiguang1

StudentID ()

Value: 1

Student ()

Name: shiguang1

NextStudentID: 2

J: 1

> Shiguang2

StudentID ()

Value: 2

Student ()

Name: shiguang2

NextStudentID: 3

J: 2

> Shiguang3

StudentID ()

Value: 3

Student ()

Name: shiguang3

NextStudentID: 4

~ Student ()

~ StudentID ()

~ Student ()

~ StudentID ()

~ Student ()

~ StudentID ()

NextStudentID: 1

Differences between the two:

 

One-dimensional pointers apply for and create three objects when creating pointers.

 

A two-dimensional pointer creates only one pointer array (3*4 bytes) when creating a pointer. The elements in the array are used to store the addresses of three objects, each object address is created by new. Therefore, the corresponding delete function should be delete p [j], rather than delete [] p.

From Study Notes of sg131971