Tcl Programming Examples

tcl while loop

tcl

#!/usr/bin/tclsh

set a 10

#while loop execution 
while { $a < 20 } {
   puts "value of a: $a"
   incr a
}

if statement

tcl

#!/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"

relational operator

tcl

#!/usr/bin/tclsh

set a 21
set b 10

if { $a == $b } {
   puts "Line 1 - a is equal to b\n"
} else {
   puts "Line 1 - a is not equal to b\n" 
}
if { $a < $b } {
   puts "Line 2 - a is less than b\n"
} else {
   puts "Line 2 - a is not less than b\n"
}
if { $a > $b } {
   puts "Line 3 - a is greater than b\n"
} else {
   puts "Line 3 - a is not greater than b\n"
}
# Lets change value of a and b
set a 5
set b 20
if { $a <= $b } {
   puts "Line 4 - a is either less than or equal to  b\n"
}
if { $b >= $a } {
   puts "Line 5 - b is either greater than  or equal to a\n"
}

single expression

tcl

#!/usr/bin/tclsh

set variableA "10"
set tcl_precision 5
set result [expr $variableA / 9.0];
puts $result

Mathematical Expression

tcl

#!/usr/bin/tclsh

set variableA "10"
set result [expr $variableA / 9];
puts $result
set result [expr $variableA / 9.0];
puts $result
set variableA "10.0"
set result [expr $variableA / 9];
puts $result

Dynamic Typing

tcl

#!/usr/bin/tclsh

set variableA "10"
puts $variableA
set sum [expr $variableA +20];
puts $sum

variable naming

tcl

#!/usr/bin/tclsh

set variableA 10
set {variable B} test
puts $variableA
puts ${variable B}

Another Reading file

tcl

#!/usr/bin/tclsh

set fp [open "input.txt" w+]
puts $fp "test\ntest"
close $fp
set fp [open "input.txt" r]

while { [gets $fp data] >= 0 } {
   puts $data
}
close $fp

Read file

tcl

#!/usr/bin/tclsh

set fp [open "input.txt" w+]
puts $fp "test"
close $fp
set fp [open "input.txt" r]
set file_data [read $fp]
puts $file_data
close $fp

Associative Array

tcl

#!/usr/bin/tclsh

set  marks(english) 80
puts $marks(english)
set  marks(mathematics) 90
puts $marks(mathematics)

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