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BC140 KiKi Design class inheritance

describe

KiKi Understand that inheritance can make code reuse , He now defines a base class shape, Private data is coordinate point x,y, Derived from it Rectangle Classes and Circle class , They all have member functions GetArea() Find the area . Derived class Rectangle Class has data ： The length and width of the rectangle ; Derived class Circle Class has data ： The radius of the circle .Rectangle Class derives square Square class , Define and test . Enter three sets of data , They are the length and width of the rectangle 、 The radius of the circle 、 The side length of a square , Output three groups of data , They are rectangles 、 round 、 The square area . PI by 3.14 Calculation .

Input description ：

Enter three lines ,

The first line is the length and width of the rectangle ,

The second line is the radius of the circle ,

The third line is the side length of the square .

Output description ：

Three elements , They are rectangles 、 round 、 The square area .

Example 1

Input ：

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7 8
10
5

     

      
1.
      
2.
      
3.
     

Copy

Output ：

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56
314
25

     

      
1.
      
2.
      
3.
     

Copy

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#include<stdio.h>
int main()
{
    float pi = 3.14;
    int c,k,r,b;    // Long   wide   radius   Side length 
    scanf("%d %d %d %d",&c,&k,&r,&b);
    printf("%d\n%g\n%d\n",c*k,pi*r*r,b*b);
}

     

      
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Function knowledge

1. Functions cannot be nested , But you can nest calls

2.printf() ： Returns the number of characters printed on the screen , If an error occurs , Return negative

3.scanf() ： Returns the number of valid characters successfully read

4. Functions can be accessed in a chain

5. You can use global variables to pass parameters

6. Functions can have no return value

7. The definition of a function can be placed anywhere , The declaration of a function must be placed before the use of the function

8. The declaration of a function simply tells the compiler the type of the return value of the function 、 Function name and parameters required by the function , The function definition is to explain how the function is implemented
9. Formal parameters are instantiated only when the function is called , To open up memory space
10. When passing parameters, whether by value or pointer , All the formal parameters get is a copy of the argument
11. Formal parameters are instantiated only when the function is called , To open up memory space
12. main The position of the function can be anywhere , Top note, but if you call those functions before the main function , Must be in main The header file that contains the life of the called function or the called function before the function .
13. Variables defined in compound statements within a function can only be used in compound statements , Not valid within the scope of this function
14. The formal parameters of a function are generally passed by pressing the stack of parameters , The formal parameters in the function are saved in the stack
15. Different functions belong to different scopes , Therefore, variables with the same name defined in different functions will not conflict
16. Variables defined in functions , It's called a local variable , Local variables can only be used in the functions they define , Variables defined within a function are valid only within the scope of this function