#include<stdio.h>
#include<iostream>
#include<GL/glut.h>
using namespace std;

int pntX1, r;

void plot(int x, int y)
{

    glBegin(GL_POINTS);
    glVertex2i(x+pmntX1, y+pntY1);
    glend();
}


void myInit(void)
{
    glClearColor(1.0, 1.0, 1.0, 1.0);
    glColor3f(o.of, o.of, o.of);
    glPointSize(4.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho 2D(0.0, 640.0, 0.0, 480.0);

}

void midPointCircleAlgo()
{

    int x = 0;
    int y = r;
    float decision = 5/4 - r;
    plot(x,y);

    while (y > x)
    {

        if (decision < 0)

        {

            x++;
            decision += 2*x+1;
        }
        else
        {
            y--;
            x++;
            decision += 2*(x-y)+1;
        }
        plot(x, y)
        plot(x, -y)
        plot(-x, y);
        plot(-x,-y);
        plot(y, x);
        plot(-y, x);
        plot(y, -x);
        plot(-y, -x);
    }
}

void myDisply(void)
{

    glClear(GL_cOLOR_BUFFER_BIT);
    glColor3f(0.0, 0.0, 0.0);
    glPointSize(1.0);

    midPointCircleAlgo()

    glFlush();
}

void main(int argc, char** argv)
{
    cout << "Enter the coordinate of the center:\n\n" <endl;

    cout << "X-coordinate   : "; cin >> pntX1;

    cout << "\nY-coordinate :"; cin >> pntY1;

    cout << "\nEnter Radius :"; cin >> r;

    glutInit(&argc, argv);
    glutinitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize (640, 480);
    glutInitWindowPosition (100, 150);
    glutCreateWindow("Line Drawing Algorithms");
    glutDisplayFunc(myDisplay);
    myInit ();
    glutMainLoop();
}

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}