These are the type of errors that occurs when incorrect logic is implemented in the code and the code produces unexpected output.
Logic errors can be the hardest to track down. Everything looks like it is working; you have just programmed the computer to do the wrong thing. Technically the program is correct, but the results won’t be what you expected.
If you didn’t check the requirements beforehand and wrote code to return the oldest user in your system when you needed the newest, you would have a logic error.
Example: Find GCD (Greatest Common Divisor) or HCF (Highest Common Factor) of two numbers that is the largest number that divides both of them.
Logic errors occur when the code doesn’t behave as expected due to flawed logic or reasoning. Unlike syntax errors, which involve incorrect syntax that prevents code from running, logic errors allow the code to run but produce unintended results.
The fact that the code can run despite these errors makes them some of the most difficult to uncover.
Common examples of logical errors in programming include:
- Flawed logic in conditional (if-else) statements or loops that cause conditions not to be evaluated as expected, leading to incorrect control flow.
- Incorrectly using logical operators (AND, OR, NOT).
- Writing algorithms that solve the wrong problem or using inappropriate algorithms for a given problem.
- Performing operations on variables with incompatible data types, especially when implicit type conversion occurs.
- Writing loops that don’t terminate properly.
Conclusion: The program runs without crashing, but it produces incorrect or unintended results due to flawed logic in the code. These errors are the most challenging to detect because the program appears to function normally, but the output is not what was expected. An example could be an incorrect mathematical formula or a condition that evaluates incorrectly.