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27
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
Variables
Logo can interpret a string of characters in four ways:
1. Numeric value
The strings “123” and “25.6” are recognized as numeric values.
2. Command
The strings “square” and “triangle”, when created in the routines defined
above, are recognized as commands.
3. Text
To print the word “house”, if one writes print house, Logo sees the word
“house” as a command. To enable Logo to treat the word “house” as text,
there must be double quote marks placed immediately before it. It also can
be written as print “house".
4. Variable name
Placing a colon “:” before a word enables Logo to read the word as a variable. In
the example above, “forward :n” enables Logo to read “:n” as a variable and
use it as input to the command “forward.”
1. Drawing Commands
forward (fd) n turtle goes forward N steps.
back (bk) n turtle goes back N steps.
left (lt) n rotate the turtle left (counterclockwise) N degrees.
right (rt) n rotate the turtle right (clockwise) N degrees.
setx n turtle goes to X = N coordinate.
sety n turtle goes to Y = N coordinate.
setxy x y turtle goes to (x,y) coordinate.
setheading (seth) n turn the turtle N degrees (clockwise) from the
straight up position.