Class :它是用户定义的数据类型,其中包含变量和函数。这就像一个对象的蓝图。默认情况下,班级成员是私人的。例如,汽车是一个对象,其颜色,设计,重量是其属性,而制动器,限速等是其功能。
句法:
class
{
private:
// Data members
........... ...... .......
public:
// Data members
// Member function
......... ........ ......
protected:
// Data members
// Member function
....... ....... ......
};
下面是C++程序来说明该类:
C++
// C++ program to illustrate class
#include
using namespace std;
// Class with data members
// and member function
class Geeks {
public:
string geekname;
int roll_no;
// Function printName
// prints the name
void printName()
{
cout << "Geekname is: "
<< geekname;
}
// Function printRollno
// prints the roll no
void printRollno()
{
cout << "Roll no is: "
<< roll_no;
}
};
// Driver Code
int main()
{
// Object of class Geeks
Geeks obj1;
// Initialize a public data
// members of class Geeks
obj1.geekname = "Geek";
obj1.roll_no = 15;
// Function Call
obj1.printName();
cout << endl;
// Function Call
obj1.printRollno();
return 0;
}
C++
// C++ program to illustrate structure
#include
using namespace std;
// Structure with data members
// and member function
struct geekyPerson {
// Data members
string name;
int age;
float salary;
// Member function to display
void display()
{
cout << "Name: " << name
<< endl;
cout << "Age: " << age
<< endl;
cout << "Salary: " << salary;
}
};
// Driver Code
int main()
{
// Instance of the structure
geekyPerson g1;
// Accessing the data by the
// dot operator
g1.name = "Geeky";
g1.age = 23;
g1.salary = 15000;
// Function Call
g1.display();
return 0;
}
C++
// C++ program to illustrate union
#include
using namespace std;
// Union declaration with the
// data members
union geeks {
int id;
int salary;
char name[30];
int age;
};
// Driver Code
int main()
{
// Instance of the union
union geeks g1;
g1.id = 1;
cout << "Id : " << g1.id
<< endl;
strcpy(g1.name, "Geeky");
cout << "Name : " << g1.name
<< endl;
g1.salary = 35000;
cout << "Salary : " << g1.salary
<< endl;
g1.age = 25;
cout << "Age : " << g1.age
<< endl;
return 0;
}
输出:
Geekname is: Geek
Roll no is: 15
说明:在上面的C++类示例中,Geeks在公共访问说明符中具有数据成员和成员函数。使用类的对象使用某些值初始化数据成员。使用该对象,将调用该类的功能。
结构:这是对变量进行分组的便捷方法。默认情况下,结构成员是公共成员。可以使用结构来有效地提高抽象级别,以改进代码。
句法:
struct
{
// Data members
....... ...... ......
// Member functions
....... ...... ......
};
下面是C++程序来说明结构:
C++
// C++ program to illustrate structure
#include
using namespace std;
// Structure with data members
// and member function
struct geekyPerson {
// Data members
string name;
int age;
float salary;
// Member function to display
void display()
{
cout << "Name: " << name
<< endl;
cout << "Age: " << age
<< endl;
cout << "Salary: " << salary;
}
};
// Driver Code
int main()
{
// Instance of the structure
geekyPerson g1;
// Accessing the data by the
// dot operator
g1.name = "Geeky";
g1.age = 23;
g1.salary = 15000;
// Function Call
g1.display();
return 0;
}
输出:
Name: Geeky
Age: 23
Salary: 15000
说明:在结构名称之前使用struct标记来定义结构。每个成员定义都是一个普通的变量定义,例如int i;或浮动f;或任何其他有效的变量定义。使用该对象,将调用结构的功能。
联合:这是用户定义的数据类型。它类似于结构。联合的所有数据成员共享相同的存储位置。工会的规模基于工会中最大成员的规模。若要将相同的内存位置用于两个或多个成员,则最好是并集。
句法:
union
{
// Data members
..... ....... .........
} union_variables;
where,
union_name − Name was given to the union.
union_variable − The object of union.
Data members -Member variables.
下面是说明联合的C++程序:
C++
// C++ program to illustrate union
#include
using namespace std;
// Union declaration with the
// data members
union geeks {
int id;
int salary;
char name[30];
int age;
};
// Driver Code
int main()
{
// Instance of the union
union geeks g1;
g1.id = 1;
cout << "Id : " << g1.id
<< endl;
strcpy(g1.name, "Geeky");
cout << "Name : " << g1.name
<< endl;
g1.salary = 35000;
cout << "Salary : " << g1.salary
<< endl;
g1.age = 25;
cout << "Age : " << g1.age
<< endl;
return 0;
}
输出:
Id : 1
Name : Geeky
Salary : 35000
Age : 25
说明:同样,在并集中,对象也用于访问数据成员和成员函数。
要从最佳影片策划和实践问题去学习,检查了C++基础课程为基础,以先进的C++和C++ STL课程基础加上STL。要完成从学习语言到DS Algo等的更多准备工作,请参阅“完整面试准备课程” 。