Results of a command - Math 101

The Tcl command for doing math type operations is expr. The following discussion of the expr command is extracted and adapted from the expr man page.

Many commands use expr behind the scenes in order to evaluate test expressions, such as if, while and for loops, discussed in later sections. All of the advice given here for expr also holds for these other commands. expr takes all of its arguments ("2 + 2" for example) and evaluates the result as a Tcl "expression" (rather than a normal command), ...