#include<iostream>
#include <GL/glut.h> 
#include<math.h>
using namespace std;
void myinit()
{
    glClearColor(1.0,1.0,1.0,0.0);
    glColor3f(0.0f,0.0f,0.0f);
    gluOrtho2D(0,640,0,480); 
    //glPointSize(4);
}
void line(int x1,int y1,int x2,int y2)
{
    glBegin(GL_LINES);
        glVertex2i(x1,y1);
        glVertex2i(x2,y2);
        glEnd();
        glFlush();
} 
void koch(int x1, int y1, int x2, int y2, int it)
{
    float angle = 60*M_PI/180; 
    int x3 = (2*x1+x2)/3;
    int y3 = (2*y1+y2)/3;
    int x4 = (x1+2*x2)/3;
    int y4 = (y1+2*y2)/3;
    int x = x3 + (x4-x3)*cos(angle)+(y4-y3)*sin(angle); 
    int y = y3 - (x4-x3)*sin(angle)+(y4-y3)*cos(angle);
    if(it > 0)
    { 
        koch(x1, y1, x3, y3, it-1);
        koch(x3, y3, x, y, it-1);
        koch(x, y, x4, y4, it-1);
        koch(x4, y4, x2, y2, it-1);
    } 
    else
    {
        line(x1, y1, x3, y3);
        line(x3, y3, x, y);
        line(x, y, x4, y4); 
        line(x4, y4, x2, y2);
    }   
}
void mydisplay()
{
    glClear(GL_COLOR_BUFFER_BIT); 
    int x1 = 100, y1 = 100, x2 = 400, y2 = 400;
    koch(x1, y1, x2, y2, 4);
}
int main(int argc, char** argv)
{
    glutInit(&argc,argv); // Initialize GLUT 
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB); // Enable buffered mode
    glutInitWindowSize(640,480); // Set the window's initial width & height
    glutInitWindowPosition(0,0);
        // Position the window's initial top-left corner
    glutCreateWindow("Koch Curve Snowflake ");
        // Create window with the given title
    glutDisplayFunc(mydisplay); // Register callback handler for window re-paint event
    myinit();
    glutMainLoop(); // Enter the infinite event-processing loop 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
}