Converting Client input char to int

Question

I'm trying to print out the temperature from a DS18B20 sensor to my app via a tpc connection. Because I have two sensors connected I will need to call the one needed by an Index. This index comes from my app and is a char value which I need to convert it to an int for comparision later. The problem I have is the conversion from to input char value to int. My code:

void loop() {
  //setting default sensor to 0
  sensorindex = 0;
  //starting server
  WiFiClient client = wifiServer.available();

  if (client) {
  Serial.write("Client connected");
          client.println("connected");
    while (client.connected()) {
      while (client.available()>0) {

        //instream from client/mobile device
        char c = client.read();
        //converting char c to int
        sensorindex = String(c).toInt() ;  
        Serial.println(sensorindex);
      }

      //comparing client input to DS18B20 sensor index
      sensors.requestTemperatures();
      if(sensorindex == 1){
           client.println(sensors.getTempCByIndex(1));
           Serial.println("Index 1");
      }
      if(sensorindex == 0){
           client.println(sensors.getTempCByIndex(0));
             Serial.println("Index 0");
      }

      delay(50);
    }

    client.stop();
    Serial.println("Client disconnected");
  }
}

The serial output:

Client connectedIndex 0
Index 0
Index 0
Index 0
Index 0
Index 0
1
0
Index 0
Index 0
Index 0
Index 0
Index 0
Index 0
Index 0
Index 0
Client disconnected

When I type in 1 from my android app it shows

1
0

in the output. What am I doing wrong?