Useful Links

C
1>  GCC Compilation Options :
http://www.thegeekstuff.com/2012/10/gcc-compiler-options/

2> 50 Linux Most Used Commands :
http://www.thegeekstuff.com/2010/11/50-linux-commands/

3>Compilation Steps :
http://www.thegeekstuff.com/2011/10/c-program-to-an-executable/

4>Make Utility :
http://www.thegeekstuff.com/2010/08/make-utility/

5>Memory Management ( Pointers) :
http://staff.um.edu.mt/csta1/courses/lectures/csa2060/c8a.html

6>Memory management :
http://shareprogrammingtips.com/c-language-programming-tips/structure-of-a-c-program-in-memory-how-heapstackdata-and-code-segments-are-stored-in-memory/

http://www.geeksforgeeks.org/memory-layout-of-c-program/

7> Dynamic Memory Allocation :
http://fresh2refresh.com/c/c-dynamic-memory-allocation/

7> Debugging in GCC -GDB- :
http://www.thegeekstuff.com/2010/03/debug-c-program-using-gdb/

Ping-Pong Game in C

Game : Ping-Pong Game
Language : C ( TURBO C Libraries used )

/*  Start of Code */
#include <stdio.h>
#include <conio.h>
#include <graphics.h>
#include <stdlib.h>
#include <bios.h>
#include <math.h>
#include <time.h>
#include <dos.h>
void game_status (int state);
int move_pad(int key);
void erase(int obj );
void ball_dynamix(void );
void play(void );
#define R_RIGHT 77 // Right_Arrow
#define R_LEFT 75 // Left_Arrow
#define R_UP 72 // Up_Arrow
#define R_DOWN 80 // Down_Arrow
#define QUIT   1 // (ESC)
#define L_RIGHT 32 //(D)
#define L_LEFT 30 //(A)
#define L_UP 17 //(W)
#define L_DOWN 31 //(S)
#define RESET 19 //(R)
#define INIT 0
#define UPDATE 10
#define X 3
#define Y 3
#define R_INIT_X_TOP 480
#define R_INIT_Y_TOP 215
#define R_INIT_X_BTM 482
#define R_INIT_Y_BTM 265
#define L_INIT_X_TOP 156
#define L_INIT_Y_TOP 215
#define L_INIT_X_BTM 158
#define L_INIT_Y_BTM 265
#define BALL_X_POS 319
#define BALL_Y_POS 240
#define SPEED_X 3
#define SPEED_Y 3

struct ball
{
int x_new;
int x_old;
int x_speed;
int y_new;
int y_old;
int y_speed;
}b;
struct pad
{
int cur_x_top;
int cur_y_top;
int cur_x_btm;
int cur_y_btm;
}r,l;

int dirn,l_score=0,r_score=0;
char ballpos[20],r_skor[10],l_skor[10];
void main()
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   int mid_x = getmaxx()/2,mid_y = getmaxy()/2; // mid_x = 239.5 , mid_y = 319.5
   printf("X = %d, Y = %d",mid_x,mid_y);
   /* initialize graphics mode */
   initgraph(&gdriver, &gmode, "\\tc\\bgi");
   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk)    /* an error occurred */
   {
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);               /* return with error code */
   }

  game_status(INIT);
  play();
  getch();
  closegraph();
}
void game_status(int state)
{
   srand(time(NULL));  // Seed ONCE
   dirn = rand()%10;
   if (state == INIT)
   {
  /* Draw the Net */
  setfillstyle(XHATCH_FILL, BLUE);
  bar(317,30,320,449);
  /* Draw the Pitch Borders */
  setcolor(WHITE);
  rectangle(20,30,619,449);
  /* Display Instructions & Other Texts */
  outtextxy (25,20,"Press ESC to exit game");
  outtextxy (25,452,"Player-1 :");
  outtextxy (515,452,"Player-2 :");
  /* Create Ball */
  setfillstyle(SOLID_FILL, BLUE);
  fillellipse(BALL_X_POS,BALL_Y_POS,3,3);
   b.x_new = BALL_X_POS;
   b.y_new = BALL_Y_POS;
   b.x_old = BALL_X_POS;
   b.y_old = BALL_Y_POS;
   b.x_speed = SPEED_X;
   b.y_speed = SPEED_Y;
   if ( dirn == 2)
   {
   b.y_speed = 0;
   printf("IN-2");
   }
   if (dirn == 7)
   {
   b.y_speed = 0;
   printf("IN-7");
   }  
 
  /* Draws Right & Left Pad*/
  setfillstyle(SOLID_FILL, GREEN);
  bar(R_INIT_X_TOP,R_INIT_Y_TOP,R_INIT_X_BTM,R_INIT_Y_BTM);
  bar(L_INIT_X_TOP,L_INIT_Y_TOP,L_INIT_X_BTM,L_INIT_Y_BTM);
  /* Initialise The Pads */
   r.cur_x_top = R_INIT_X_TOP;
   r.cur_y_top = R_INIT_Y_TOP;
   r.cur_x_btm = R_INIT_X_BTM;
   r.cur_y_btm = R_INIT_Y_BTM;
   l.cur_x_top = L_INIT_X_TOP;
   l.cur_y_top = L_INIT_Y_TOP;
   l.cur_x_btm = L_INIT_X_BTM;
   l.cur_y_btm = L_INIT_Y_BTM;
   }
    if ( state == RESET )
   {
    erase(0);
erase(1);
erase(2);
game_status(INIT);
   }
     if ( state == QUIT )
   {
    exit(0);
   }
}
int move_pad(int key)
{
switch(key)
{
case R_LEFT:
if (r.cur_x_top > 325)
{
erase(1);
setfillstyle(SOLID_FILL, GREEN);
bar(r.cur_x_top-X,r.cur_y_top,r.cur_x_btm-X,r.cur_y_btm);
r.cur_x_top -= X;
r.cur_x_btm -= X;
}
break;
case R_RIGHT:
if (r.cur_x_btm > 315 && r.cur_x_btm <610)
{
erase(1);
setfillstyle(SOLID_FILL, GREEN);
bar(r.cur_x_top+X,r.cur_y_top,r.cur_x_btm+X,r.cur_y_btm);
r.cur_x_top += X;
r.cur_x_btm += X;
}
break;
case R_UP:
if (r.cur_y_top > 35)
{
erase(1);
setfillstyle(SOLID_FILL, GREEN);
bar(r.cur_x_top,r.cur_y_top-Y,r.cur_x_btm,r.cur_y_btm-Y);
r.cur_y_top -= Y;
r.cur_y_btm -= Y;
}
break;
case R_DOWN:
if (r.cur_y_btm < 445)
{
erase(1);
setfillstyle(SOLID_FILL, GREEN);
bar(r.cur_x_top,r.cur_y_top+Y,r.cur_x_btm,r.cur_y_btm+Y);
r.cur_y_top += Y;
r.cur_y_btm += Y;
}
break;
case L_LEFT:
if (l.cur_x_top > 23)
{
erase(2);
setfillstyle(SOLID_FILL, GREEN);
bar(l.cur_x_top-X,l.cur_y_top,l.cur_x_btm-X,l.cur_y_btm);
l.cur_x_top -= X;
l.cur_x_btm -= X;
}
break;
case L_RIGHT:
if (l.cur_x_btm > 20 && l.cur_x_btm < 310 )
{
erase(2);
setfillstyle(SOLID_FILL, GREEN);
bar(l.cur_x_top+X,l.cur_y_top,l.cur_x_btm+X,l.cur_y_btm);
l.cur_x_top += X;
l.cur_x_btm += X;
}
break;
case L_UP:
if (l.cur_y_top > 30)
{
erase(2);
setfillstyle(SOLID_FILL, GREEN);
bar(l.cur_x_top,l.cur_y_top-Y,l.cur_x_btm,l.cur_y_btm-Y);
l.cur_y_top -= Y;
l.cur_y_btm -= Y;
}
break;
case L_DOWN:
if ( l.cur_y_btm < 445)
{
erase(2);
setfillstyle(SOLID_FILL, GREEN);
bar(l.cur_x_top,l.cur_y_top+Y,l.cur_x_btm,l.cur_y_btm+Y);
l.cur_y_top += Y;
l.cur_y_btm += Y;
}
break;
}
return 1;
//printf("R:%d:%d:%d:%d\n",r.cur_x_top,r.cur_y_top,r.cur_x_btm,r.cur_y_btm);
}
void erase(int obj)
{
  if ( obj== 0)  // Erase Ball
  {
   b.x_old = b.x_new;
   b.y_old = b.y_new;
   setcolor (BLACK);
   setfillstyle(SOLID_FILL, BLACK);
   fillellipse(b.x_new,b.y_new,3,3);
   }
  if ( obj== 1)  // Erase Right Paddle
  {
   setfillstyle(SOLID_FILL, BLACK);
   bar(r.cur_x_top,r.cur_y_top,r.cur_x_btm,r.cur_y_btm);
  }
  if ( obj== 2)  // Erase Left Paddle
  {
   setfillstyle(SOLID_FILL, BLACK);
   bar(l.cur_x_top,l.cur_y_top,l.cur_x_btm,l.cur_y_btm);
  }
}
void play(void )
{
int move;
while (1)
{

  delay (20); // Reduce game speed to human playable level
       if (inportb (0X60) == R_RIGHT)  move_pad (R_RIGHT);
       if (inportb (0X60) == R_LEFT)   move_pad (R_LEFT);
       if (inportb (0X60) == R_UP)     move_pad (R_UP);
       if (inportb (0X60) == R_DOWN)   move_pad (R_DOWN);
  if (inportb (0X60) == L_RIGHT)  move_pad (L_RIGHT);
       if (inportb (0X60) == L_LEFT)   move_pad (L_LEFT);
       if (inportb (0X60) == L_UP)     move_pad (L_UP);
       if (inportb (0X60) == L_DOWN)   move_pad (L_DOWN);
  if (inportb (0X60) == RESET)    game_status(RESET);
  if (inportb (0X60) == QUIT)     game_status(QUIT);
  ball_dynamix();
  setfillstyle(XHATCH_FILL, BLUE);
  bar(317,30,320,449);
 }
}
void ball_dynamix()
{
   erase(0);
   switch (dirn)
   {
    case 0: case 1: // RIGHT-UP
b.x_new = b.x_new + b.x_speed;
b.y_new = b.y_new - b.y_speed;
break;
case 2: // RIGHT
b.x_new = b.x_new + b.x_speed;
    b.y_new = b.y_new + b.y_speed;
break;
    case 3: case 4: // RIGHT-DOWN
b.x_new = b.x_new + b.x_speed;
b.y_new = b.y_new + b.y_speed;
break;
case 5: case 6: // LEFT-UP
b.x_new = b.x_new - b.x_speed;
b.y_new = b.y_new - b.y_speed;
break;
case 7: // LEFT
b.x_new = b.x_new - b.x_speed;
b.y_new = b.y_new + b.y_speed;
break;
case 8: case 9: // LEFT-DOWN
b.x_new = b.x_new - b.x_speed;
    b.y_new = b.y_new - b.y_speed;
break;
}
   setfillstyle (SOLID_FILL,GREEN); // Display New postion.
   fillellipse ( b.x_new, b.y_new , 3,3);
   if ( b.y_new - 3 < 35 ) b.y_speed = -b.y_speed; // Reflect From Top
   if ( b.y_new + 3 > 445 ) b.y_speed = -b.y_speed; // Reflect From Bottom
   if ( b.x_new - 3 < 25 ) // Reflect From Left
   {
   b.x_speed = -b.x_speed;
   l_score++;
   }
   if ( b.x_new + 3 > 615 ) // Reflect From Right
   {
   b.x_speed = -b.x_speed;
   r_score++;
   }
 
// Deflect Left UP
   if  ((b.y_new >= l.cur_y_top && b.y_new <= l.cur_y_btm-35 ) && (b.x_new >= l.cur_x_top - 6 && b.x_new <= l.cur_x_btm + 6))
    {
b.x_speed = -b.x_speed;
b.y_speed = -2;
}
// Deflect Left Straight
if  ((b.y_new >= l.cur_y_top+15 && b.y_new <= l.cur_y_btm-15 ) && (b.x_new >= l.cur_x_top - 6 && b.x_new <= l.cur_x_btm + 6))
    {
b.x_speed = -b.x_speed;
}
// Deflect Left DOWN
   if  ((b.y_new >= l.cur_y_top+35 && b.y_new <= l.cur_y_btm ) && (b.x_new >= l.cur_x_top - 6 && b.x_new <= l.cur_x_btm + 6))
    {
b.x_speed = -b.x_speed;
b.y_speed = 2;
}

// Deflect Right UP
   if  ((b.y_new >= r.cur_y_top && b.y_new <= r.cur_y_btm-35 ) && (b.x_new >= r.cur_x_top - 6 && b.x_new <= r.cur_x_btm + 6))
    {
b.x_speed = -b.x_speed;
b.y_speed = -2;
}
// Deflect Right Straight
   if  ((b.y_new >= r.cur_y_top+15 && b.y_new <= r.cur_y_btm-15 ) && (b.x_new >= r.cur_x_top - 6 && b.x_new <= r.cur_x_btm + 6))
       {
b.x_speed = -b.x_speed;
}
// Deflect Right DOWN
   if  ((b.y_new >= r.cur_y_top+35 && b.y_new <= r.cur_y_btm ) && (b.x_new >= r.cur_x_top - 6 && b.x_new <= r.cur_x_btm + 6))
    {
b.x_speed = -b.x_speed;
b.y_speed = 2;
}
 }
/*  End of Code */

                     ENJOY!!!!!

Matlab Useful Commands

	Commands	Purpose
General	Ver	Gets Details of all the toolbox installed with version #'s
	Version	MATLAB Version Running
	clc	Clear Command Window
	clear all	Clear complete workspace
	clear variable	Clears the variable specified
	Exit	Exits from matlab
	Quit
	Ctrl + C	Stop the current execution ( in Command window )
	lookfor	Search for similar commands
Workspace	who	Shows variable names in the currently available workspace
	whos	Shows variable names & Details in the currenty available workspace
	exist	Check for existence of the variable in the workspace
	save filename	Save as filename.mat to disk
	Load filename	Load filename.mat from disk
Variables	Global	Declares variable as global
	persistent	Defines a persistent variable ( static )
	a = [ 1 , 2 ,3 ]	Create Row Matrix
	a = [ 1  2 3 ]
	b = [ 1; 2; 3 ]	Creates Column Matrix
	c = [1 2 3 ; 4 5 6 ; 7 8 9]	Creates a 3*3 Matrix
Directory / System	Dir	Lists contents of Current Directory
	cd newdir	Change directory  newdir
	cd ..	Goes to current directorie's parent directory
	mkdir newdir	creates a new directory newdir
	rmdir newdir	Deletes directory newdir
	rmdir ('newdir','s')	Deletes directory newdirand any folders inside recursively
	delete newfile	delete's the file newfile
	pwd	Displays the current working directory
	date	displays the current system date
	type newfile	Display the contents of newfile
	what	Lists all the matlab files in the current directory
	diary	Switches on/off the diary for recording contents of the command window

Bit Operations

Useful C Programs
1> Bit Operations
          Set , Clear, Check bit.

#include<stdio.h>.
void showbit(int);
int setbit(int,int);
int clearbit(int,int);
int rtshift(int,int);
int lfshift(int,int);
int checkbit(int,int);
int dectohex(int);
int bintohex(int);
int main()
{
    int a,b,value;
    value =(10);
    printf("%d:\n",value);
    showbit(value);
    a = rtshift(value ,2);
    printf("%d:\n",a);
    showbit(a);
    b = lfshift(value ,2);
    printf("%d:\n",b);
    showbit(b);
    checkbit(value,1)? printf("Bit Set"):printf("Bit Clear");
    return 0;
}
void showbit(int a)
{
    int i,d=0;
    for(i=31;i>=0;i--)
    {
     if(!(a &(1<<i)))
     {
      printf("0");
      d++;
     }
      else
     {
      printf("1");
      d++;
     }
     if (d == 4)
     {
     printf(" ");
     d=0;
     }
    }
 printf("\n");

//Simpler way for above
//!(a &(1<<i))?printf("0"):printf("1");
}
int rtshift(int val,int rtshft)
{
return (val>>rtshft);
}
int lfshift(int val,int lfshft)
{
return (val<<lfshft);
}

int setbit(int val,int pos)
{
    return (val|(1<<pos));
}
int clearbit(int val,int pos)
{
    return (val&=~(1 << (pos-1)));
}
int checkbit(int val,int pos)
{
    return (val & (1<<pos));
}