The execution controllers enable you — as their name implies — to control execution
If you have done some programming in KTurtle you have might noticed that the turtle can be very quick at drawing. This command makes the turtle take it a little more easy.
- wait
wait X
wait makes the turtle wait for X seconds.
repeat 36 [
forward 5
turnright 10
wait 0.5
]
This code draws a circle, but the turtle will wait half a second
after each step. This gives the impression of an easy-moving turtle.
- if
if question [ ... ]
The code that is placed between the brackets will only be executed if the answer to the question is “true”. Please read for more information on questions in the question section.
x = 6
if x > 5 [
print "x is greater than five!"
]
On the first line x is set to 6. On the second line the question x > 5 is asked. Since the answer to this question is “true” the execution controller if will allow the code between the brackets to be executed
- while
while question [ ... ]
The execution controller while is a lot like if. The difference is that while keeps repeating the code between the brackets till the answer to the question is “false”.
x = 1
while x < 5 [
forward 10
wait 1
x = x + 1
]
On the first line x is set to 1. On the second line the question x < 5 is asked. Since the answer to this question is “true” the execution controller while starts executing the code between the brackets till the answer to the question is “false”. In this case the code between the brackets will be executed 4 times, because every time the fifth line is executed x increases by 1..
If not, in other words: "else"
- else
if question [ ... ] else [ ... ]
else can be used in addition to the execution controller if. The code between the brackets after else is only executed if the answer to the question that is asked is “false”.
x = 4
if x > 5 [
print "x is greater than five!"
] else [
print "x is smaller than six!"
]
The question asks if x is greater than 5. Since x is set to 4 on the first line the answer to the question is “false”. This means the code between the brackets after else gets executed.
- for
for start point to end point [ ... ]
The for loop is a “counting loop”, i.e. it keeps count for you.
for x = 1 to 10 [
print x * 7
forward 15
]
Every time the code between the brackets is executed the x is increased by 1, till x reaches the value of 10. The code between the brackets prints the x multiplied by 7. After this program finishes its execution you will see the times table of 7 on the canvas.