Avoiding pitfalls

Computers don't make mistakes

So, the good news is that computers don't make mistakes.

The bad news is that, because it's up to humans like us to tell computers what to do, mistakes can and often do creep in.

Bugs

These mistakes, or bugs, can cause a program to produce unexpected results or stop working altogether.

OK computer:
remember 0 as my_number
repeat until my_number is less than 0:
 add 1 to my_number
then display my_number

//Output Below

...

See that? Because my_number will never be less than 0, this so-called infinite loop will never get to display my_number.

Debugging

Debugging, which means finding and fixing bugs, is an important part of programming. Can you spot a bug in this program?

OK computer:
remember "Walter" as my_name
add " White" to my_name
display my name
  • Yes, in display my name

Perfect! Because my name misses an underscore, the computer can't make sense of line 3.

Syntax bugs

Instructions need to follow special rules. When we break these rules, computers don't know what we want them to do.

What rule would make sense here?

OK computer:
if it is teatime
then display "time for afternoon tea"

//Output Below

time for afternoon tea

See that? These so-called syntax bugs can be typos or words that computers don’t understand.

Logic bugs

When a program has a logic bug, it doesn't crash but doesn't act as intended either. Can you spot such a bug in this program?

OK computer:
remember 42 as my_age
if my_age is greater than 65
or my_age is greater than 12
then display "20% discount"
else display "no discount"
  • Yes, we need to check if my_age is less than 12

Fantastic! We need to check if my_age is less than 12 or anybody above 12 gets a discount.

Documenting programs

As programs become more and more powerful, their instructions become harder and harder to read. How might we be able to prevent that?

  • By providing comments for complicated instructions

Yes! Using comments and meaningful names for variables and functions, programs become easier to understand and debug.

Testing

Before we release a program, we should perform a range of tests. Why might this be important?

  • Because there may be severe bugs in the program

Great! Even though we won't be able to find every bug in a program, we shouldn't release a program with severe bugs.

Author

Laryea

Web Developer