Parsing a part of a string of unknown length

Thanks @michinyon, but I'm not quite sure how to implement it into the code. Here is what I have so far:

String command; // the command string
String title; // the title string *This is the string I'm after!*

void setup() {
  Serial.begin(115200); // start serial at 115200
  pinMode(13, OUTPUT); // an indicator for debugging
  Serial.println("Ready."); // indicate that we are connected and ready to go
}
void loop() {
  if (Serial.available()) {  // when the serial port is available
    char c = Serial.read(); // read the characters
    if (c == '\n') { // if there is a new line
      parseCommand(command); // go and parse the command string
      command = ""; // after the command is parsed, reset it
    }
    else { // if the command is not parsed yet (no new line),
      command += c; // keep adding to the command string
    }
    Serial.println(title); // print the title string
  }
}
void parseCommand(String com) {
  fun_a("TITLE:", "\n");
}


int fun_a(  char*  string,    char*  substring )
{
}


int fun_b (  char* string,  char* substring1,  char* substring2 )
{
     int p= fun_a( string, substring1 );
    int q = fun_a( string, substring2 );
    if ( p >= 0 && q >=0 && q>p ) return p ;
    else return -1 ;
}

I have tried a few different things, but all I get is blank output with a new line feed. Thanks for the help again, I will understand this!