Instruction manual

25
Drawing a square consists of going forward and turning right four times. This
can be written more concisely using a repeat command:
to square
repeat 4 [forward 10 right 90]
end
The repeat command has two sets of additional information or input - a number
indicating the number of times to repeat the command (“4”) and the list of
commands to be repeated “[forward 10 right 90]”. Once this routine is defined,
one need only to write “square” and Logo will draw a 10-step square at the
current Turtle location.
This routine can draw squares of only one size. To enable it to draw squares of
varying sizes, define the command with an input:
to square :n
repeat 4 [forward :n right 90]
end
This command contains additional information or input “:n” which indicates the
variable size of the square. Once this routine is defined, one can write “square
5” to have Logo draw a 5-step square at the current Turtle location. “square 10”
will Logo draw a 10-step square, “square 15” will Logo draw a 15-step square,
and so on.
A routine to draw an equilateral triangle is as follows:
to triangle :n
right 30
repeat 3 [forward :n right 120]
left 30
end
After the routines for a square and a triangle have been defined, a routine to
draw a simple house can be made from a square with a triangle on top:
to house :n
square :n
forward :n
triangle :n
back :n
end