Bizarre serial input behavior - Input from experienced users appreciated!

I'd prefer to not use a delimiter. This is for an ME control systems class and I don't want to have to tell me professor to setup the serial monitor a certain way before he runs it, but it I have to than so be it.

If changing the serial monitor setup is the main issue with not using a delimiter, then use a delimiter that is typed in the serial monitor at the end of the data. the below uses a , as the delimiter and no default serial monitor change is required. Just tell the professor to type a , at the end of the data and hit the keyboard enter key or click send in the serial monitor.

//zoomkat 3-5-12 simple delimited ',' string parce 
//from serial port input (via serial monitor)
//and print result out serial port
// CR/LF could also be a delimiter

String readString;

void setup() {
  Serial.begin(9600);
  Serial.println("serial delimit test 1.0"); // so I can keep track of what is loaded
}

void loop() {

  //expect a string like wer,qwe rty,123 456,hyre kjhg,
  //or like hello world,who are you?,bye!,
  
  if (Serial.available())  {
    char c = Serial.read();  //gets one byte from serial buffer
    if (c == ',') {
      //do stuff
      Serial.println(readString); //prints string to serial port out
      readString=""; //clears variable for new input      
     }  
    else {     
      readString += c; //makes the string readString
    }
  }
}