programming-for-dummies

284
Adding Comments to Source Code
By placing such a descriptive comment at the beginning of every subprogram,
other people can understand what the subprogram does and who to
contact (blame) without having to examine the source code line by line.
Debugging
Comments can temporarily ignore lines of code for testing. For example, suppose
your program included the following:
Y = log(Y) – (500 + sin(Angle))
X = Rate * exp(X) / Y
PRINT “The value of x = “, X
If you wanted to see how your program would work if you eliminated the
first line of code and replaced it with a new line of code, you could erase the
top line and type a new line, such as
Y = cos(Angle) * Y
X = Rate * exp(X) / Y
PRINT “The value of x = “, X
Now if you wanted to replace the top line with the previously erased line,
you’d have to delete the top line and retype the preceding line all over again.
A simpler method would be to comment out the top line and type in a new
line, such as
‘ Y = log(Y) – (500 + sin(Angle))
Y = cos(Angle) * Y
X = Rate * exp(X) / Y
PRINT “The value of x = “, X
This causes the compiler to ignore the top line (treating it as a comment).
Now if you want to “insert” the top line back into the program, you can comment
out the second line and remove the comment symbol from the first
line:
Y = log(Y) – (500 + sin(Angle))
‘ Y = cos(Angle) * Y
X = Rate * exp(X) / Y
PRINT “The value of x = “, X
The preceding code is equivalent to the following:
Y = log(Y) – (500 + sin(Angle))
X = Rate * exp(X) / Y
PRINT “The value of x = “, X