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Tcl Cheat Sheet


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variables
$a
set a {a string}
global a Use a global variable within a procedure.
comments
# a comment
set a $b ;# not much to say about this
generic expression
$a ? $b : $c
arithmetic
Basic arithmetic uses the expr command.
expr 44*4
strings
{what ever}
$a$b concatenation
string length $a
string compare $a $b returns 1, 0, or -1.
numbers
$a + $b
$a - $b
- $a
$a * $b
$a / $b
abs($a)
exp($a)
pow($base,$exp)
sin($a) [etc.]
lists
list $elem1 $elem2
concat $list1 $list2
lappend listvarname $newelem
lindex $list $n nth element
llength $list
concat $list1 $list2
functions
    [foo 1 {a b c}]
proc foo {x y} {
    action1
    action2
    return ... $x ...
}
sentences
0 false

Anything but 0 is taken as true.

$a == $b numeric
$a != $b numeric
$a != $b numeric
$a < $b numeric
$a <= $b numeric
$a >= $b numeric
$a > $b numeric
$a && $b logical
$a || $b logical
! $a logical
actions
set a 44
foo 1 {a b c}

proc is an action.

if {$s} {
    action1
} elseif {$t} {
    action2
} else {
    action3
}
while {$s} {
    action
}
foreach user $users {
    action
}
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