TCL Procedure Programs all types

TCL script examples with sample programs

1.simple tcl procedure program call by value

proc sum {arg1 arg2 } {
set x [expr $arg1+$arg2];
return $x
}
set var [sum 2 3]
set n [expr {$var+10}]
puts “the return value is $var and n is $n”

o/p:
the return value is 5 and n is 15

2.tcl procedure program by passing default arguments

proc sum {arg1 {arg2 20} } {
set x [expr $arg1+$arg2]
return $x
}
set var1 [sum 2 ]
puts $var1
set var2 [sum 2 8]
puts $var2

o/p:
22
10

simple tcl procedure program
proc sm { a b} {
puts $a+$b  }

sm 4 5

o/p:
4+5

simple tcl procedure program by giving one default arguments
proc sm { a {b 34} } {
puts [expr $a+$b]  }

set var [sm 5 ]

o/p:
39

tcl procedure program should not be like below

proc sm { {a 34} b } {
puts [expr $a+$b]  }

set var [sm 5 ]

o/p:
——–
wrong # args: should be “sm ?a? b”
while executing
“sm 5 ”

tcl procedure program,giving all arguments as optional

proc sum { {arg1 10} {arg2 20}  } {
set x [expr $arg1+$arg2]
return $x
}
set var1 [sum 2 ]
puts $var1
set var2 [sum 2 8]
puts $var2
set var3 [sum]
puts $var3

o/p:
22
10
30

tcl procedure program using args should not be like below

proc sum { arg1  args {arg2 20} } {
set x [expr $arg1+$arg2]
return $x
}
set var1 [sum 2 ]
puts $var1
set var2 [sum 2 8]
puts $var2
set var3 [sum 2 56 67 87 243 567 789]
puts $var3

o/p:——–
wrong # args: should be “sum arg1 args ?arg2?”
while executing
“sum 2 ”

tcl procedure program using args keyword

proc sum { arg1  {arg2 20} args} {
set x [expr $arg1+$arg2]
foreach i $args {
puts $i }
return $x
}
set var1 [sum 2 ]
puts $var1
set var2 [sum 2 8]
puts $var2
set var3 [sum 2 34 56 "lmn" abc 'xyz' 789]
puts $var3

o/p:
22
10
56
lmn
abc
‘xyz’
789
36

tcl procedure program upvar -call by reference :

proc callbyref name1 {
puts $name1
upvar $name1 a
set a [expr {$a+5}]
puts $a }

set x 10
callbyref x
puts $x

o/p:
x
15
15

proc sample { } {
global a b
puts “$a  $b”
}
sample

#puts “$a  $b”
——–
can’t read “a”: no such variable
while executing
“puts “$a  $b”"
(procedure “sample” line 3)
invoked from within
“sample”

tcl procedure program using uplevel

proc sample {varname first last body} {
upvar $varname v
for {set v $first} {$v<=$last} {incr v} {
uplevel $body  }
}

set v { }
sample i 1 5 {
lappend v [expr $i*$i]
}

puts $v

o/p:
1 4 9 16 25