Types of Errors
Computer Science: OCR GCSE, topic 2.3.8
Types of Errors
Syntax errors
- A syntax error is a mistake in the way the code is written.
- It is similar to a spelling or grammar mistake in English.
- Syntax errors prevent programs from running as a translator needs code to be syntactically correct.
- Syntax errors are some of the easier bugs to fix in a broken program.
Examples of syntax errors
- prnt("Hello, world!");
- Incorrect subroutine identifier.
- newbalance = newBalance * 1.05;
- Wrong capitalisation in variable identifier.
- myBoolean = True NOT False;
- NOT does not take two operands.
Logic errors
- Logic errors are mistakes in the logic of the program.
- Programs will run, but their outcome will not be as intended.
- They are much more difficult to debug than syntax errors.
- Logic errors are hard to detect because the translator will not detect them for us.
Examples of logic errors
- Many logic errors arise from the use of the wrong boolean operator, e.g. mixing up AND and OR.
- Many logic errors arise from putting menu options the wrong way around in a selection statement.
Runtime errors
- Runtime errors are errors that happen while the program is running.
- Runtime errors cannot be found during translation.
- These errors can only be detected while a program is running.
- The chance of experiencing a runtime error can be reduced through testing.
- Runtime errors are the trickiest of the three types of errors because they are not always found during development. Software users may first encounter runtime errors.
Examples of runtime errors
- Bad inputs that throw an unhandled exception.
- Receiving unexpected or corrupted data.
- Running out of memory.
Test yourself on Types of Errors
Why do syntax errors prevent programs from running?
Which of the following are syntax errors?
Would the following code cause a syntax error?
print("Hello, world!")Why is it more difficult to detect a logic error than a syntax error?
You translate a program and see this error:
ERROR LINE 13 "x = True NOT False" Incorrect use of operator
Is this a logic error?