Mastering Tcl: A Beginner's Guide to Tool Command Language part 2

Logical Operations in Tcl

1. AND Operation

        set A "1"
set B "0"
set c [expr "$A && $B"]
puts "This is the result for AND operation $c"

# Output: This is the result for AND operation 0


    

2. OR Operation

        set set A "1"
set B "1"

set c [expr "$A || $B"]
puts "This is the result for OR operation $c"

# Output: This is the result for OR operation 1


    

3. NOT Operation

Example 1

        set A "0"
set B "1"

set c [expr "!$B"]
puts "This is the result for NOT operation $c"

# Output: This is the result for NOT operation 0


    

Example 2

        set A "0"
set B "1"

set c [expr "!$A"]
puts "This is the result for NOT operation $c"

# Output: This is the result for NOT operation 1


    

Bitwise Operations in Tcl

Bitwise operations work on the bit level of variables.

1. AND Operation

        set A "218"
set B "235"

set c [expr "($A & $B)"]
puts "This is the result for AND operation $c"

# Output: This is the result for AND operation 202


    

Explanation:

• A in decimal: 218 → binary: 1010 1101
• B in decimal: 235 → binary: 1011 1110
• AND each bit: 1010 1100 → decimal: 202

2. OR Operation

        set A "218"
set B "235"

set c [expr "($A | $B)"]
puts "This is the result for OR operation $c"

# Output: This is the result for OR operation 251


    

Explanation:

• A in decimal: 218 → binary: 1010 1101
• B in decimal: 235 → binary: 1011 1110
• OR each bit: 1011 1111 → decimal: 251

Other Logical Operations:

• ^ XOR operation
• << Shift left operation
• >> Shift right operation

hints : don't write numbers on decimal system in TCL shell

Wrong  Result

Lists in Tcl

1. Creating Lists

Method 1: Using spacing and double quotes

        set L1 "1 2 3"
# Output: 1 2 3

    

Method 2: Using spacing and curly brackets

        set L2 {A B C}
# Output: A B C

    

Method 3: Using list command

        set L3 [list apple banana mango]
# Output: apple banana mango
    

2. List Commands

        set L1 "1 2 3"
puts "$L1"
# Output: 1 2 3 
    

Get the length of a list

        set L1 "1 2 3"
llength $L1
# Output: 3 
    

Get elements of a list

        set L1 "1 2 3"
lindex $L1 0
# Output: 1
lindex $L1 1
# Output: 2
lindex $L1 2
# Output: 3

    

Get the last element of a list

        set L1 "1 2 3"
lindex $L1 end
# Output: 3

    

Get the element before the last in a list

        set L1 "1 2 3"
lindex $L1 end-1
# Output: 2

    

Sorting a list

        set L3 [list d b c a]
lsort $L3

# Output: a b c d

    

Append an item to a list

        set fruits [list apple banana cherry]
lappend fruits "date"
puts $fruits

# Output: apple banana cherry date 

    

Get a sublist

        set fruits [list apple banana cherry]
puts [lrange $fruits 1 2]

# Output: banana cherry 

    

Loop Structures in Tcl

1. For Loop

        for {set i 0} {$i < 5} {incr i} {
    puts "Iteration $i"
}

    

Output:

Iteration 0
Iteration 1
Iteration 2
Iteration 3
Iteration 4

2. While Loop

        set i 0
while {$i < 5} {
    puts "Iteration $i"
    incr i
}

    

Output:

Iteration 0
Iteration 1
Iteration 2
Iteration 3
Iteration 4

3. Foreach Loop

        set L1 "0 1 2 3"
foreach List_item $L1 {
    puts "Element $List_item"
}

    

Output:

Element 0
Element 1
Element 2
Element 3