// C++ Headers
#include <string>
#include <iostream>

// OpenGL / glew Headers
#define GL3_PROTOTYPES 1
//#include <GL/glew.h>

// SDL2 Headers
#include <SDL2/SDL.h>

#include <EGL/egl.h>
#include <GLES/gl.h>

#include <android/sensor.h>
#include <android/log.h>
#include <android_native_app_glue.h>
//#include "SDL/SDL_opengl.h"

//Screen attributes
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;
#include <GLES2/gl2.h>
#include <SDL2/SDL.h>

struct myData {
    SDL_Window *window;
    SDL_GLContext context;
};

const GLchar vertex[] =
       "attribute vec4 position;    \n"
    "void main()                  \n"
    "{                            \n"
    "   gl_Position = vec4(position.xyz, 1.0);  \n"
    "}                            \n";

const GLchar fragment[] =
    "precision mediump float;\n"
    "void main()                                  \n"
    "{                                            \n"
    "  gl_FragColor = vec4 (0.0, 1.0, 1.0, 1.0 );\n"
    "}                                            \n";



GLuint loadShader(GLuint program, GLenum type, const GLchar *shaderSrc) {
    GLuint shader;
    shader = glCreateShader(type);
    glShaderSource(shader, 1, &shaderSrc, NULL);
    glCompileShader(shader);
    glAttachShader(program, shader);
    return 0;
}

int sdlInit(myData *data) {
    SDL_Init(SDL_INIT_VIDEO);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);

    data->window = SDL_CreateWindow("Demo", 0, 0, 512, 512, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
    data->context = SDL_GL_CreateContext(data->window);

    return 0;
}

int glInit(myData *data) {
    GLuint programObject;
        GLuint vbo;
    glGenBuffers(1, &vbo);

    GLfloat vertices[] = {0.0f, 0.9f, 0.9f, -0.9f, -0.9f, -0.9f};


    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    programObject = glCreateProgram();
    loadShader(programObject, GL_VERTEX_SHADER, vertex);
    loadShader(programObject, GL_FRAGMENT_SHADER, fragment);
    glLinkProgram(programObject);
    glUseProgram(programObject);
    GLint posAttrib = glGetAttribLocation(  programObject , "position");
    glEnableVertexAttribArray(posAttrib);
    glVertexAttribPointer(posAttrib,2, GL_FLOAT, GL_FALSE, 0, 0);
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glViewport(0, 0, 512, 512);

    return 0;
}

int loopFunc(myData *data) {
    SDL_Event event;
    while (SDL_PollEvent(&event)) {
        if (event.type == SDL_QUIT) {
            return 1;
        }
    }

      // Clear the screen to black
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // Draw a triangle from the 3 vertices
        glDrawArrays(GL_TRIANGLES, 0, 3);
    SDL_GL_SwapWindow(data->window);

    return 0;
}

void sdlQuit(myData *data) {
    SDL_GL_DeleteContext(data->context);
    SDL_DestroyWindow(data->window);
    SDL_Quit();
    return;
}

int main() {
    myData data;

    sdlInit(&data);

    glInit(&data);

    while (!loopFunc(&data));

    sdlQuit(&data);

    return 0;
}
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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
}