Compare two string in a while loop

Here is a program that just use a single caracter :

int valeurLue;
float tension;
char bitlu;

void setup() {
  Serial.begin(9600);
  Serial.println("attente");
}

void loop() {
  
  //initialize
  valeurLue = analogRead(3);
  tension = valeurLue * 4.88;
  if (tension > 2500) {
    bitlu = '1';
  }
  else {
    bitlu = '0';
  }
  
  //while loop
  while (bitlu != '1') {
    delay(1000);
    valeurLue = analogRead(3);
  tension = valeurLue * 4.88;
  Serial.println(tension);
  if (tension > 2500) {
    bitlu = '1';
  }
  else {
    bitlu = '0';
  }
  Serial.println(bitlu);
  }
  
  Serial.println("fin du test");
  delay(5000);
}