A variable declaration may give an initial value to a variable,
otherwise its initial value is undefined, as in
Two or more variable declarations can be combined into one unit
A constant declaration must give an initial value to a constant
Each execution of a declaration causes a new elaboration of the initialization. In this way a constant may have a different value after each declaration executed. The term ``constant'' is therefore somewhat misleading: its value is not changeable by an assignment, therefore it is constant over part or all of the program.