seeking out the tag on .txt into SD card - RFID

Hi, guys

I am trying to make an RFID with the list of tags inside the SD card, so that the program looks for the authorized tag inside the .txt

with this code below, I was able to read the tags, however it reads all at once. Is there any way to make the sketch look for the tag within .txt more effectively?

myFile = SD.open("ANV.txt");
    if (myFile) {
      while (myFile.available() && (c2 == 0)) {
        caractere = 0;
        while (myFile.available() && (caractere != ';') && (caractere != 13) && (c1 == 0)) {
          caractere = myFile.read();
          if ((caractere != ';') && (caractere != 13)) {
            usuario.concat(caractere);
          }
        }


         Serial.println(usuario);

taking into account that the tags are stored as follows in .txt

56341126;Adam
159687;Joe
19465789612;Susan

thanks!

Why do you have two while(myFile.available() statements, one nested inside the other in your snippet?

Why did you waste our time by posting only a snippet?

You can speed up reading text files by using fixed length records. Then, you can read a record in one step, instead of looking at each character, to see if it is the end of record marker.

You can store the data read from the file in a string (a NULL terminated array of chars) far faster than you can store it in a String, with all the dynamic memory allocation and copying that happens when you add one character at a time to the String instance.

EVERYTHING that you can do with a String can be done using a string, with less code and less memory.