ANSWERS TO SELF TEST ON CHAPTER 2
1. An internal number store is like a pigeon hole which you can name and put numbers into.
2. A LET statement which uses a particular name for the first time will cause a pigeon hole to be
created and named, for example
LET count = 1 (1 point)
A READ statement which uses a name for the first time will have the same effect, for example:
READ count (1 point)
3. You can find the value of a pigeon hole with a PRINT statement.
4. The technical name for a pigeon hole is 'variable' because its values can vary as a program runs.
5. A variable gets its first value when it is first used in a LET statement, INPUT statement or READ
statement.
6. A change in the value of a variable is usually caused by the execution of a LET statement.
7. The = sign in a LET statement represents an operation:
'Evaluate whatever is on the right hand side and place it in the pigeon hole named on the left
hand side: that is 'Let the left hand side become equal to the right hand side'.
8. An unnumbered statement is executed immediately.
9. A numbered statement is not executed immediately. It is stored.
10. The quotes in a PRINT statement enclose text which is to be printed.
11. When quotes are not used you are printing out the value of a variable.
12. An INPUT statement makes the program pause so that you can type data at the keyboard.
13. DATA statements are never executed.
14. They are used to provide values for the variables in READ statements.
15. The technical word for the name of a pigeon hole is 'identifier'.
16. Example answers:
i. day
ii. day_23
iii. day_of_week (3 points)
17. The space bar is especially important for putting spaces after or before keywords so that they
cannot be taken as identifiers (names) chosen by the user.
18. Freely chosen identifiers are important because they help you to make programs easier to
understand. Such programs are less prone to errors and more adaptable.
CHECK YOUR SCORE
18 to 21 is very good. Carry on reading.
16 or 17 good but re-read some parts of chapter two.
14 or 15 fair, but re-read some parts of chapter two and do the test again.
Under 14 you should work carefuly through chapter two again and repeat the test.
To Next Page
Loading...
Need help?
General
