The compound assignment operator provides a shortcut notation x op= y; for the expression x = x op y; where x,y are variables and op one of the supported operators: +,-,*,/,%...

The compound assignment operator provides only the shortcut notation x += y; for the expression x = x + y; where x,y are variables.

The compound assignment operator allows to join two strings of text as c << "text A" << "text B";

The compound assignment operator provides the shortcut notation x++; for the expression x = x + 1;