PROGRAM ZA GENERIRANJE CAPTCHA I PROVJERU KORISNIKA

A CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) test je kojim se utvrđuje je li korisnik čovjek ili ne.
Dakle, zadatak je generirati jedinstveni CAPTCHA svaki put i reći je li korisnik čovjek ili nije tražeći od korisnika da unese isti CAPTCHA kao što je automatski generiran i provjeravajući korisnički unos pomoću generiranog CAPTCHA.
Primjeri:

CAPTCHA: x9Pm72se Input: x9Pm62es Output: CAPTCHA Not Matched CAPTCHA: cF3yl9T4 Input: cF3yl9T4 Output: CAPTCHA Matched

Skup znakova za generiranje CAPTCHA pohranjen je u nizu znakova chrs[] koji sadrži (a-z A-Z 0-9), stoga je veličina chrs[] 62.
Za generiranje jedinstvenog CAPTCHA svaki put kada se generira nasumični broj pomoću funkcije rand() (rand()%62) koja generira nasumični broj između 0 do 61 i generirani nasumični broj se uzima kao indeks za niz znakova chrs[] tako generira novi znak captcha[] i ova se petlja pokreće n (duljina CAPTCHA) puta za generiranje CAPTCHA zadane duljine.

Algoritam:

Prvo deklarirajte i definirajte funkciju checkCaptcha() koja uzima dva parametra niza i vraća booleovu vrijednost.
Unutar funkcije checkCaptcha() usporedite dva parametra niza pomoću funkcije compare() i vratite true ako su isti; inače vrati false.
Deklarirajte i definirajte funkciju generateCaptcha() koja uzima cjelobrojni parametar i vraća vrijednost niza.
Unutar funkcije generateCaptcha() inicijalizirajte vremensku varijablu pomoću funkcije time() i postavite generator slučajnih brojeva pomoću funkcije srand().
Deklarirajte niz znakova koji sadrži sve znakove koji će biti uključeni u CAPTCHA i dodijelite ga varijabli pokazivača char.
Generirajte nasumični CAPTCHA niz navedene duljine uzastopnim dodavanjem nasumičnih znakova iz niza znakova u varijablu niza pomoću funkcije push_back().
Vrati generirani CAPTCHA niz.
Unutar funkcije main() deklarirajte varijablu niza pod nazivom captcha i pozovite funkciju generateCaptcha() duljine 9 za generiranje nasumičnog CAPTCHA niza.
Ispišite generirani CAPTCHA niz na konzoli.

CPP

// C++ program to automatically generate CAPTCHA and // verify user #include    using namespace std; // Returns true if given two strings are same bool checkCaptcha(string& captcha string& user_captcha) {  return captcha.compare(user_captcha) == 0; } // Generates a CAPTCHA of given length string generateCaptcha(int n) {  time_t t;  srand((unsigned)time(&t));  // Characters to be included  char* chrs = 'abcdefghijklmnopqrstuvwxyzABCDEFGHI'  'JKLMNOPQRSTUVWXYZ0123456789';  // Generate n characters from above set and  // add these characters to captcha.  string captcha = '';  while (n--)  captcha.push_back(chrs[rand() % 62]);  return captcha; } // Driver code int main() {  // Generate a random CAPTCHA  string captcha = generateCaptcha(9);  cout << captcha;  // Ask user to enter a CAPTCHA  string usr_captcha;  cout << 'nEnter above CAPTCHA: ';  cin >> usr_captcha;  // Notify user about matching status  if (checkCaptcha(captcha usr_captcha))  printf('nCAPTCHA Matched');  else  printf('nCAPTCHA Not Matched');  return 0; }

Java

// Java pprogram to automatically generate CAPTCHA and // verify user import java.util.*; import java.io.*; class GFG {    // Returns true if given two strings are same  static boolean checkCaptcha(String captcha String user_captcha)  {  return captcha.equals(user_captcha);  }    // Generates a CAPTCHA of given length  static String generateCaptcha(int n)  {  //to generate random integers in the range [0-61]  Random rand = new Random(62);     // Characters to be included  String chrs = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';    // Generate n characters from above set and  // add these characters to captcha.  String captcha = '';  while (n-->0){  int index = (int)(Math.random()*62);  captcha+=chrs.charAt(index);  }    return captcha;  }    // Driver code  public static void main(String[] args)throws IOException  {  BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));    // Generate a random CAPTCHA  String captcha = generateCaptcha(9);  System.out.println(captcha);    // Ask user to enter a CAPTCHA  System.out.println('Enter above CAPTCHA: ');  String usr_captcha = reader.readLine();    // Notify user about matching status  if (checkCaptcha(captcha usr_captcha))  System.out.println('CAPTCHA Matched');  else  System.out.println('CAPTCHA Not Matched');  } } // This code is contributed by shruti456rawal

Python3

# Python program to automatically generate CAPTCHA and # verify user import random # Returns true if given two strings are same def checkCaptcha(captcha user_captcha): if captcha == user_captcha: return True return False # Generates a CAPTCHA of given length def generateCaptcha(n): # Characters to be included chrs = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789' # Generate n characters from above set and # add these characters to captcha. captcha = '' while (n): captcha += chrs[random.randint(1 1000) % 62] n -= 1 return captcha # Driver code # Generate a random CAPTCHA captcha = generateCaptcha(9) print(captcha) # Ask user to enter a CAPTCHA print('Enter above CAPTCHA:') usr_captcha = input() # Notify user about matching status if (checkCaptcha(captcha usr_captcha)): print('CAPTCHA Matched') else: print('CAPTCHA Not Matched') # This code is contributed by shubhamsingh10

using System; using System.Text; class GFG {  // Returns true if given two strings are same  static bool CheckCaptcha(string captcha string user_captcha)  {  return captcha.Equals(user_captcha);  }  // Generates a CAPTCHA of given length  static string GenerateCaptcha(int n)  {  // to generate random integers in the range [0-61]  Random rand = new Random();  // Characters to be included  string chrs = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';  // Generate n characters from above set and  // add these characters to captcha.  StringBuilder captcha = new StringBuilder();  while (n-- > 0)  {  int index = rand.Next(62);  captcha.Append(chrs[index]);  }  return captcha.ToString();  }  // Driver code  static void Main(string[] args)  {  // Generate a random CAPTCHA  string captcha = GenerateCaptcha(9);  Console.WriteLine(captcha);  // Ask user to enter a CAPTCHA  Console.WriteLine('Enter above CAPTCHA: ');  string usr_captcha = Console.ReadLine();  // Notify user about matching status  if (CheckCaptcha(captcha usr_captcha))  Console.WriteLine('CAPTCHA Matched');  else  Console.WriteLine('CAPTCHA Not Matched');  } }

JavaScript

// JavaScript program to automatically generate CAPTCHA and // verify user // Returns true if given two strings are same function checkCaptcha(captcha user_captcha) { return captcha.localeCompare(user_captcha) == 0; } // Generates a CAPTCHA of given length function generateCaptcha(n) { // Characters to be included const chrs = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'; let captcha = ''; for (let i = 0; i < n; i++) { captcha += chrs[(Math.floor(Math.random() * chrs.length))]; } return captcha; } // Driver code function main() { // Generate a random CAPTCHA const captcha = generateCaptcha(9); console.log(captcha); // Ask user to enter a CAPTCHA const usr_captcha = prompt('Enter above CAPTCHA:'); // Notify user about matching status if (checkCaptcha(captcha usr_captcha)) console.log('CAPTCHA Matched'); else console.log('CAPTCHA Not Matched'); } main();

Izlaz:

CAPTCHA: cF3yl9T4 Enter CAPTCHA: cF3yl9T4 CAPTCHA Matched

Vremenska složenost: Na)
Složenost prostora: O(1)

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Program za generiranje CAPTCHA i provjeru korisnika