Learn TCL with Real Code Examples

set count 0
set isDark 0

proc updateUI {} {
    global count isDark
    puts "Counter: $count"
    puts "Theme: [expr {$isDark ? \"Dark\" : \"Light\"}]"
}

proc increment {} {
    global count
    incr count
    updateUI
}

proc decrement {} {
    global count
    incr count -1
    updateUI
}

proc reset {} {
    global count
    set count 0
    updateUI
}

proc toggleTheme {} {
    global isDark
    set isDark [expr {1 - $isDark}]
    updateUI
}

# Simulate actions
updateUI
increment
increment
toggleTheme
decrement
reset

Demonstrates a simple counter with theme toggling using Tcl variables and console output.

set a 10
set b 20
set sum [expr {$a + $b}]
puts "Sum: $sum"

Adds two numbers and prints the result.

set fact 1
for {set i 1} {$i <= 5} {incr i} {
    set fact [expr {$fact * $i}]
}
puts "Factorial: $fact"

Calculates factorial of 5 using a loop.

set fib0 0
set fib1 1
puts $fib0
puts $fib1
for {set i 3} {$i <= 10} {incr i} {
    set next [expr {$fib0 + $fib1}]
    puts $next
    set fib0 $fib1
    set fib1 $next
}

Generates first 10 Fibonacci numbers.

set a 15
set b 25
if {$a > $b} {
    set max $a
} else {
    set max $b
}
puts "Max: $max"

Finds the maximum of two numbers.

set nums {1 2 3 4 5}
set sum 0
foreach n $nums {
    set sum [expr {$sum + $n}]
}
puts "Sum: $sum"

Sums elements of an array.

set nums {1 2 3 4 5}
foreach n $nums {
    if {[expr {$n % 2}] == 0} {
        puts "Even: $n"
    }
}

Prints even numbers from an array.

set count 3
if {$count < 5} {
    incr count
}
puts "Count: $count"

Increment counter only if less than 5.

set count 0
incr count
incr count
incr count
puts "Count: $count"
set count 0
puts "Count after reset: $count"

Counter that increments and can be reset.

set isDark 0
puts "Theme: [expr {$isDark ? \"Dark\" : \"Light\"}]"
set isDark [expr {1 - $isDark}]
puts "Theme: [expr {$isDark ? \"Dark\" : \"Light\"}]"
set isDark [expr {1 - $isDark}]
puts "Theme: [expr {$isDark ? \"Dark\" : \"Light\"}]"

Toggles theme multiple times.