if (n)
Execute scripts conditionally
SYNOPSIS
if expr1 ?then? body1 elseif expr2 ?then? body2 elseif ... ?else? ?bodyN?
DESCRIPTION
The if command evaluates expr1 as an expression (in the
same way that expr evaluates its argument). The value of the
expression must be a boolean
(a numeric value, where 0 is false and
anything is true, or a string value such as true or yes
for true and false or no for false);
if it is true then body1 is executed by passing it to the
Tcl interpreter.
Otherwise expr2 is evaluated as an expression and if it is true
then body2 is executed, and so on.
If none of the expressions evaluates to true then bodyN is
executed.
The then and else arguments are optional
``noise words'' to make the command easier to read.
There may be any number of elseif clauses, including zero.
BodyN may also be omitted as long as else is omitted too.
The return value from the command is the result of the body script
that was executed, or an empty string
if none of the expressions was non-zero and there was no bodyN.
KEYWORDS
boolean, conditional, else, false, if, true
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