Captcha program in C

 Captcha program using graphics in C

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Captcha  is used to strong the security of your software. captcha ensure your security from artificial robots (programs) 

Functions used :

• initgraph()
• settextstyle()
• outtextxy()

#include <stdlib.h>

#include <dos.h>

#include <graphics.h>

int main()

{

  int i = 0, key, n, x, gd = DETECT, gm;

  char a[10];

 

  initgraph(&gd, &gm, "C:\\turboc3\\bgi");

 

  x = getmaxx()/2;

 

   settextstyle(SCRIPT_FONT, HORIZ_DIR, 5);

   settextjustify(CENTER_TEXT, CENTER_TEXT);

  setcolor(GREEN);

  outtextxy(x, 20, "CAPTCHA");

   settextstyle(SCRIPT_FONT, HORIZ_DIR, 2);

  outtextxy(x, 125, "Press any key to change the generated \"captcha\"");

  outtextxy(x, 150, "Press escape key to exit...");

 

  setcolor(WHITE);

  setviewport(100, 200, 600, 400, 1);

  setcolor(RED);

  randomize();

 

  while (1)

  {

    while (i < 6)

    {

      n = random(3);

 

      if (n == 0)

        a[i] = 65 + random(26);    /* 65 is the ASCII value of A */

      else if (n == 1)

        a[i] = 97 + random(26);    /* 97 is the ASCII value of a */

      else

        a[i] = 48 + random(10);    /* 48 is the ASCII value of 0 */

      i++;

    }

    a[i] = '\0';

    outtextxy(210, 100, a);

    key = getch();

 

    if (key == 27)  /* escape key */

      exit(0);

    clearviewport();

    i = 0;

  }

}