d)
Comments
***********
You can add comments in the functions you write up, in the "New
function..." or "Function editor..." windows ; do not put comments in
the console, as these will be lost and serve no purpose. The program
ignores these comments. There are two types of comments : line
comments and section comments
Line comments allow comments on one line only. The comments start out
with a double slash ( // ). For example, the following
instructions:
forward(10);
// right(90);
forward(20);
is equivalent to:
forward(30);
because the instruction right(90); is bypassed.
Section comments allow putting in a complete paragraph as an
explanation or comment on certain instructions. They start out with
slash asterisk ( /* ) and end with asterisk slash ( */ ). For
example, the following instructions :
forward(10);
/* right(90);
forward();
this is also a comment !
*/
forward(20);
is equivalent to:
forward(30);
Note: You can also nest the two types of comments. For example
:
/* this is a comment
// this is also a comment
this is still a comment !
*/
forward(20);
Ending comments
**************
To stop the execution of a function, you can hit simultaneously
command and period ( . ) at any time.
Don't mix the term " variable " and the term " function ". For
example, if you carry out pen color(blue); , then the turtle becomes
blue. However, if you carry out instead pen color=blue;, then a new
variable will be created. Its name is " pen color " and its value is
blue. This second instruction will
not change the color of the turtle
to blue.
Mask() and unmask(); accelerate by up to 50 % elaborate functions,
but slow down shorter ones.
Logo is not, in this version 1.0 of Learn and Play , a complex
language. For example, one cannot write :
variable = (12+8)*6;
instead, one must write :
variable = 12+8
variable = variable *6;
Accordingly, one cannot write :
if ((12==3) and (13==9))
{
//instructions
}
but rather :
if (12==3)
{
if (13==9)
{
//instructions
}
}