What am I doing wrong with String object

Projects Programming
1 
  String str;
  str = "startCycle() took ";
  //str += String(lNewTime - lLastTime); 
  str.concat(" milliseconds to complete...");
  Serial.println(str);

Why wont the concatenation functions and operators work?

All I get output is "startCycle() took ".

2

What am I doing wrong with String object

Using them at all.

Why wont the concatenation functions and operators work?

The concatenation operator won't work because it is commented out.

There is no proof that the concat() method doesn't work.

There is NO reason to concatenate those three values. It takes exactly the same amount of time to send out the serial port the data using three Serial.print() statements as it does to send the data using one Serial.print() statements. You'll be a lot happier programming the Arduino when you accept that fact.