Laker Tcl Reference

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Tcl Variables and Variable Substitution
Variables in Tcl can be considered as boxes in which various types of data can be
stored. These variables are given names, which are then used to access the values
stored in them.
Tcl variables need not be declared before they are used. These variables are
simply created when they are first assigned values, using the set command, as
illustrated below.
set varName varValue
Tcl variables can be deleted by using the unset command as follows:
unset varName
The value stored in a variable can be accessed by prefacing the variable name
with a dollar sign (“$”). This is known as Variable Substitution, and is described
as follows.
set a 100