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A SIMPLE COMPUTER LANGUAGE
LOGO
LOGO Introduction
http://pages.intnet.mu/jhbpage/Program/Logo/logo.htm
Logo is the simplest programming language. It was developed by Seymour Papert in 1968. It was developed originally as a teaching tool.
Though Logo is a complete language it is mainly used for drawing.
The Logo Environment
Basic Logo Commands
Instruction Shortcut Description
SHOWTURTLE ST Shows the Turtle on the screen
HIDETURTLE HT Hides the Turtle from the screen
FORWARDnumberFD Moves the Turtle forward according to the number indicated
BACK number BK Moves the Turtle back according to the number indicated
RIGHT angle RT Changes the direction of the Turtle by turning it to the right
LEFT angle LT Changes the direction of the Turtle by turning it to the left
CLEARSCREEN CS Erase the picture before a new picture is drawn
How to draw a 100 by 100 square in Logo?
Step 1
FORWARD 100
Step 2
RIGHT 90
How to draw a 100 by 100 square in Logo?
Step 3
FORWARD 100
Step 4
RIGHT 90
How to draw a 100 by 100 square in Logo?
Step 5
FORWARD 100
Step 6
RIGHT 90
How to draw a 100 by 100 square in Logo?
Step 7
FORWARD 100
Step 8
HIDETURTLE
Procedures
A procedure has 3 parts:1.It must start with the reserved word “TO”, followed by a one word procedure name.2.The main body is made up of primitives3.The procedure ends up with word “END”
A Scalene Triangle
TO scaleneCSFD 100 RT 150FD 50HOMEHTEND
An Isosceles Triangle
TO isoscelesCSRT 20FD 100 RT 140FD 100HOMEHTEND
A Pentagon
TO pentagonCSFD 100 RT 72FD 100 RT 72FD 100 RT 72FD 100 RT 72FD 100 RT 72HTEND
Looping
TO pentagonCSFD 100 RT 72FD 100 RT 72FD 100 RT 72FD 100 RT 72FD 100 RT 72HTEND
TO pentagonCSREPEAT 5 [FD 100 RT 72]HTEND
A Rectangle
TO rectangleCSFD 100 RT 90FD 50RT 90FD 100 RT 90FD 50RT 90HTEND
A Rectangle
TO rectangleCSFD 100 RT 90FD 50RT 90FD 100 RT 90FD 50RT 90HTEND
TO rectangleCSRepeat 2 [FD 100 RT 90FD 50RT 90]HTEND
An Equilateral Triangle
TO equilateralCSFD 100 REPEAT 2[RT 120FD 100]HTEND
TO equilateralCSFD 100 RT 120FD 100 RT 120FD 100 HTEND
A Kite
TO kiteCSFD 90BK 30RT 90FD 30BK 60LT 45FD SQRT (2*(30*30))RT 90FD SQRT (2*(30*30))HOMEFD 60LT 90FD 30HOMEEND
A Kite
TO kiteCSFD 90BK 30RT 90FD 30BK 60LT 45FD SQRT (2*(30*30))RT 90FD SQRT (2*(30*30))HOMEFD 60LT 90FD 30HOMEEND
Loop and Double Loops
Try each of the following:(Reset the screen before each try)1.FD 50 RT 452.REPEAT 4 [ FD 50 RT 45 ]3.REPEAT 8 [ FD 50 RT 45 ]4.REPEAT 2 [REPEAT 8 [ FD 50 RT 45 ] RT 45] 5.REPEAT 3 [REPEAT 8 [ FD 50 RT 45 ] RT 45]6.REPEAT 4 [REPEAT 8 [ FD 50 RT 45 ] RT 45]7.REPEAT 8 [REPEAT 8 [ FD 50 RT 45 ] RT 45]
Double Loops
TO NREPEAT 8 [REPEAT 8 [ FD 50 RT 45 ] RT 45] END
Loop
REPEAT 12 [ FD 100 RT 150 ]
Double Loops
REPEAT 72 [ REPEAT 360 [ FD 1 RT 1 ] RT 5 ]
Double Loops
TO CPERSPECTIVEREPEAT 4 [REPEAT 4 [FD 100 RT 90] FD 100 DOWN 90END
Double Loops
TO RPERSPECTIVEREPEAT 45 [ REPEAT 360 [ FD 2 RT 2 ] RR 8 ]END
Basic Logo Commands
Instruction Shortcut Description
PU Pen Up
PD Pen Down
PPT Pen Paint
SETXT num1 num2
SETXY Moves the Position X, Y