Can't setup an if for this code

/**************************************************************************/
/*! 
    @file     readMifare.pde
    @author   Adafruit Industries
	@license  BSD (see license.txt)

    This example will wait for any ISO14443A card or tag, and
    depending on the size of the UID will attempt to read from it.
   
    If the card has a 4-byte UID it is probably a Mifare
    Classic card, and the following steps are taken:
   
    - Authenticate block 4 (the first block of Sector 1) using
      the default KEYA of 0XFF 0XFF 0XFF 0XFF 0XFF 0XFF
    - If authentication succeeds, we can then read any of the
      4 blocks in that sector (though only block 4 is read here)
	 
    If the card has a 7-byte UID it is probably a Mifare
    Ultralight card, and the 4 byte pages can be read directly.
    Page 4 is read by default since this is the first 'general-
    purpose' page on the tags.


This is an example sketch for the Adafruit PN532 NFC/RFID breakout boards
This library works with the Adafruit NFC breakout 
  ----> https://www.adafruit.com/products/364
 
Check out the links above for our tutorials and wiring diagrams 
These chips use SPI or I2C to communicate.

Adafruit invests time and resources providing this open source code, 
please support Adafruit and open-source hardware by purchasing 
products from Adafruit!

*/
/**************************************************************************/
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_PN532.h>

// If using the breakout with SPI, define the pins for SPI communication.
//#define PN532_SCK  (2)
//#define PN532_MOSI (3)
//#define PN532_SS   (4)
//#define PN532_MISO (5)

// If using the breakout or shield with I2C, define just the pins connected
// to the IRQ and reset lines.  Use the values below (2, 3) for the shield!
#define PN532_IRQ   (2)
#define PN532_RESET (3)  // Not connected by default on the NFC Shield

// Uncomment just _one_ line below depending on how your breakout or shield
// is connected to the Arduino:

// Use this line for a breakout with a software SPI connection (recommended):
//Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);

// Use this line for a breakout with a hardware SPI connection.  Note that
// the PN532 SCK, MOSI, and MISO pins need to be connected to the Arduino's
// hardware SPI SCK, MOSI, and MISO pins.  On an Arduino Uno these are
// SCK = 13, MOSI = 11, MISO = 12.  The SS line can be any digital IO pin.
//Adafruit_PN532 nfc(PN532_SS);

// Or use this line for a breakout or shield with an I2C connection:
Adafruit_PN532 nfc(PN532_IRQ, PN532_RESET);

#if defined(ARDUINO_ARCH_SAMD)
// for Zero, output on USB Serial console, remove line below if using programming port to program the Zero!
// also change #define in Adafruit_PN532.cpp library file
   #define Serial SerialUSB
#endif

void setup(void) {
  #ifndef ESP8266
    while (!Serial); // for Leonardo/Micro/Zero
  #endif
  Serial.begin(115200);
  Serial.println("Hello!");

  nfc.begin();

  uint32_t versiondata = nfc.getFirmwareVersion();
  if (! versiondata) {
    Serial.print("Didn't find PN53x board");
    while (1); // halt
  }
  // Got ok data, print it out!
  Serial.print("Found chip PN5"); Serial.println((versiondata>>24) & 0xFF, HEX); 
  Serial.print("Firmware ver. "); Serial.print((versiondata>>16) & 0xFF, DEC); 
  Serial.print('.'); Serial.println((versiondata>>8) & 0xFF, DEC);
  
  // configure board to read RFID tags
  nfc.SAMConfig();
  
  Serial.println("Waiting for an ISO14443A Card ...");
}


void loop(void) {
  uint8_t success;
  uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };  // Buffer to store the returned UID
  uint8_t uidLength;                        // Length of the UID (4 or 7 bytes depending on ISO14443A card type)
    
  // Wait for an ISO14443A type cards (Mifare, etc.).  When one is found
  // 'uid' will be populated with the UID, and uidLength will indicate
  // if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
  success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength);
  
  if (success) {
    // Display some basic information about the card
    Serial.println("Found an ISO14443A card");
    Serial.print("  UID Length: ");Serial.print(uidLength, DEC);Serial.println(" bytes");
    Serial.print("  UID Value: ");
    nfc.PrintHex(uid, uidLength);
    Serial.println("");

    if (uidLength == 4)
    {
      // We probably have a Mifare Classic card ... 
      Serial.println("Seems to be a Mifare Classic card (4 byte UID)");
	  
      // Now we need to try to authenticate it for read/write access
      // Try with the factory default KeyA: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF
      Serial.println("Trying to authenticate block 4 with default KEYA value");
      uint8_t keya[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
	  
	  // Start with block 4 (the first block of sector 1) since sector 0
	  // contains the manufacturer data and it's probably better just
	  // to leave it alone unless you know what you're doing
      success = nfc.mifareclassic_AuthenticateBlock(uid, uidLength, 4, 0, keya);
	  
      if (success)
      {
        Serial.println("Sector 1 (Blocks 4..7) has been authenticated");
        uint8_t data[16];
		
        // If you want to write something to block 4 to test with, uncomment
		// the following line and this text should be read back in a minute
        //memcpy(data, (const uint8_t[]){ 'a', 'd', 'a', 'f', 'r', 'u', 'i', 't', '.', 'c', 'o', 'm', 0, 0, 0, 0 }, sizeof data);
         //success = nfc.mifareclassic_WriteDataBlock (4, data);

        // Try to read the contents of block 4
        success = nfc.mifareclassic_ReadDataBlock(4, data);
		
        if (success)
        {
          // Data seems to have been read ... spit it out
          Serial.println("Reading Block 4:");
          nfc.PrintHexChar(data, 16);
          Serial.println("");
          // Wait a bit before reading the card again
          delay(1000);
          nfc.mifareclassic_ReadDataBlock(4, data);
     [b] if(success == "61 64 61 66 72 75 69 74 2E 63 6F 6D 00 00 00 00  adafruit.com...."){
      Serial.println("Access Granted");
    } else {
      Serial.println("Access Denied, Wrong Card");
    }[/b]
        }
        else
        {
          Serial.println("Ooops ... unable to read the requested block.  Try another key?");
        }
      }
      else
      {
        Serial.println("Ooops ... authentication failed: Try another key?");
      }
    }
}
}

Im confused with setting up the NFC Reader so when it reads the 4th data line, if it matches then it display "Access Granted" while if it didn't match, it will display "Access Denied, Wrong Card". My board is Arduino Uno, with the NFC Reader Module PN532 using I2C Mode. Im using the Adafruit PN532 Library with the name "readMifare". The card reading is fine, just want to setup if the specific line matched the text, it will display the text. Or should I change the keya value eventhough I don't know how to do that. My main source of programming the cards is using the same module tho, since my Phone doesn't support NFC.

Please always do an Auto Format (Tools > Auto Format in the Arduino IDE or Ctrl + B in the Arduino Web Editor) on your code before posting it. This will make it easier for you to spot bugs and make it easier for us to read.

Awijaya:

if(success == "61 64 61 66 72 75 69 74 2E 63 6F 6D 00 00 00 00  adafruit.com...."){

Your first problem is that you're using the wrong variable name. success is an int8_t that indicates the whether the read was successful. It does not contain the data that was actually read. The variable you are using for that purpose is named, appropriately enough, data.

The second problem is that you can't do a comparison operation like this. Instead, use strcmp:
http://www.cplusplus.com/reference/cstring/strcmp/