+=
as in "variable += variable".
The plus sign and assignment operator sequence (+=) is short-hand for adding a number or string to a variable.
1. This is an auto-increment operator when preceded by a numeric variable.
Example
counter = length(line);
counter += 1; # Add one to the value of counter
2. It is an auto append operator when preceded by a string variable.
Example
title = "Summary Report for ";
title += date + " -- Page " pagno; # Construct the title
Last modified date: 02/01/2024