Learn C Language Programming with Free Lessons & Tips

#include

#include

void main()

{

float rad;

const float pi=3.1412f;

const char newline='\n';

float area_circle,circum_circle;

clrscr();

printf("Enter radius of a circle:");

scanf("%f",&rad);

area_circle=pi*rad*rad;

printf("Area of a circle:%f %c",area_circle,newline);

circum_circle=2*(pi*rad);

printf("Circumference of a circle:%f",circum_circle);

getch();

}

// Sample program in C

// Standard Library/Header files

#include

#include

// Main function   

(Program execution starts here)

Int main()

{

// Function for cleaning screen 

clrscr();

// Function for printing statement on console

printf("Hello World");

//Function for holding the screen at runtime

getch();

return 0;

}

Yes, "C" is a sea, with C, you write high-level programs, assembly level using #Pragma & handle peripheral devices directly, With curses & 'C' you can play with "C and implement a graphical user interface for Linux", and the more  :) you play with ASCII and Colour background in MS-DOS environment. Even much more 'C' language can do. I know this much.

Using recursion;

#include<iostream>

void printNTimes(int nTimes)
{
if(nTimes <= 0)
return;
std::cout<<"I love programming ";
printNTimes(--nTimes);
}

int main()
{
int n = 0;
std::cin>>n;
printNTimes(n);
}

These rules are instrumental when you design your class.

When you create/write a new class, you always think of 5 place holder methods in it.

Earlier it was three, but after C++ 11 it became 5.

They are: 

1. Constructor 
2. Copy Constructor
3. Assignment operator; After C++11 - 
4. Move Copy constructor 
5. Move Assignment operator.

• Rule of 0 means, your class is designed in a way, such that you don't need any of 1,2,3,4,5
• Rule of 3 means, you need 1,2,3
• Rule 3 of 5 means, you need all 1,2,3,4,5

Best case is to design a class so that you have a rule of 0. But it's not always possible.

It will depend on the nature of your class members. It's bad practice to have them as raw pointers because then you have to write these constructors carefully and also think about resource leakage. Sometimes, we make them shared pointer or unique pointer etc. to reduce our work of writing these constructors and methods. If your class members are themselves following the rule of 0,3,5 etc., then it will also affect your decision whether you have to give all 5 or 0 or 3.

In a nutshell, it's always a good practice to think about these five methods, whenever you write a new class. 

Good question!!