Tcl - If Statement

An if statement consists of a Boolean expression followed by one or more statements.

Syntax

The syntax of an 'if' statement in Tcl language is −

if {boolean_expression} {
   # statement(s) will execute if the Boolean expression is true
}

If the Boolean expression evaluates to true, then the block of code inside the if statement will be executed. If Boolean expression evaluates to false, then the first set of code after the end of the 'if' statement (after the closing curly brace) will be executed.

Tcl language uses the expr command internally and hence it's not required for us to use expr statement explicitly.

Flow Diagram

Example

#!/usr/bin/tclsh

set a 10
 
#check the boolean condition using if statement
if { $a < 20 } {
   # if condition is true then print the following 
   puts "a is less than 20" 
}
puts "value of a is : $a" 

When the above code is compiled and executed, it produces the following result −

a is less than 20
value of a is : 10