_THE TCL PROGRAMMING LANGUAGE_
by John K. Ousterhout


Example 1: 



(a)

Enter:           expr 3 << 2
Returned value:  12

(b)

Enter:           expr 14.1*6
Returned value:  84.6

(c)

Enter:           expr (3 > 4) || (6 <= 7)
Returned value:  1
   


Example 2: 

button .b -text "Hello, world!" -command exit
pack .b


Example 3: 

#!/usr/local/bin/wish -f
button .b -text "Hello, world!" -command exit
pack .b


Example 4:

(a) 

-command "puts Good-bye!; exit" 


(b)

destroy .b
source hello


Example 5: 

(a)

Enter:           set a 44
Returned value:  44
(b)

Enter:           expr $a*4
Returned value:  176


(c)

Enter:            set a 44
                  set b [expr $a*4]
Returned value:   176


(d)

set x \$a
set newline \n


Example 6: 

(a)

proc power {base p} {
   set result 1
   while {$p0} {
      set result [expr $result*$base]
      set p [expr $p-1]
   }
return $result


(b)
Enter:            power 2 6
Returned value:   64
   
Enter:           power 1.15 5
Returned value:  2.01136



Example 6: 

(a)

proc power {base p} {
   set result 1
   while {$p0} {
      set result [expr $result*$base]
      set p [expr $p-1]
   }
return $result


(b)
Enter:            power 2 6
Returned value:   64
   
Enter:           power 1.15 5
Returned value:  2.01136


Example 7: 


(a)

while (p>0) {
   result *= base;
    p -= 1;
}


(b)

while {$p>0} {
   set result [expr $result*$base]
   set p [expr $p-1]
}


(c)

set {$p>0} {
    set result [expr $result*$base]
    set p [expr $p-1]
}


Example 8:

#!/usr/local/bin/wish -f
proc power {base p} {
   set result 1
   while {$p>0} {
          set result [expr $result*$base]
          set p [expr $p-1]
   }
   return $result
}
entry .base -width 6 -relief sunken -textvariable base
label .label1 -text "to the power"
entry .power -width 6 -relief sunken -textvariable power

label .label2 -text "is"
label .result -textvariable result
pack .base .label1 .power .label2 .result -side left \
   -padx 1m -pady 2m
bind .base <Return> {set result [power $base $power]}


Example 9: 

(a)
Enter:            exec grep #include tk.h
Returned value:   #include <tcl.h>
                  #include <X11/Xlib.h>
                  #include <stddef.h>


(b)

#!/usr/local/bin/wish -f
set id 0
entry .entry -width 30 -relief sunken -textvariable cmd
pack .entry -padx 1m -pady 1m
bind .entry <Return> {
   set id [expr $id + 1]
   if {$id > 5} {
        destroy .b[expr $id - 5]
   }
   button .b$id -command "exec <@stdin >@stdout $cmd" \
        -text $cmd
   pack .b$id -fill x
   .b$id invoke
   .entry delete 0 end
}


Example 10:

(a)
 .entry configure -background yellow


(b)
  .b1 configure -foreground brown 
  .b1 flash>