Declaring Integer Variables
As with ordinary variables, integer variables need not be declared. A variable can simply be given an integer value, and then used in an arithmetic expression.
$ X=12 $ ((Y=X * 3)) $ print $Y 36
However, variables can be explicitly declared integer type by using the typeset –i command. The following example sets the DAYS and MONTHS variables to be integer type:
$ typeset —i DAYS MONTHS=12
There is also another command called integer, which is equivalent to typeset –i. It could be used to declare the DAYS and MONTHS variables like this:
$ integer DAYS MONTHS=12
Variables do not have to be explicitly declared integer type to be used in arithmetic expressions. It may improve performance, but what you really gain ...