Question

Suppose you write a program that is supposed to compute the interest on a bank account at a bank that computes interest on a daily basis, and suppose you incorrectly write your program so that it computes interest on an annual basis. What kind of program error is this?

Short answer

Answer: Semantic error

Step-by-step solution

Understanding different types of program errors

Three main types of program errors exist: syntax errors, runtime errors, and semantic errors. Syntax errors occur when the program contains incorrect code in terms of the programming language rules. Runtime errors happen during program execution and result in crashes or unexpected behavior. Semantic errors refer to the situation when the code is syntactically correct and does not crash during execution, but it does not produce the expected output due to a flaw in the program logic.

Analyzing the given situation

In this problem, we are told that the program computes interest on an annual basis instead of a daily basis. Since the program runs and computes interest, it doesn't have syntax errors or runtime errors. However, the output it produces is incorrect due to a flaw in the program logic (calculating interest annually instead of daily), which indicates a semantic error.

Identifying the type of program error

Given the information from Step 2, we can conclude that the type of program error in this situation is a semantic error. This is because the program runs, but its output is incorrect due to a logic flaw - calculating interest on an annual basis instead of a daily basis.

Key concepts

Semantic Error

When your program compiles and runs but does not produce the outcome you intended, you're dealing with a semantic error. Consider it like telling someone the wrong address; your instructions are clear and understood (the syntax is correct), but they'll end up at the wrong destination (the semantics are flawed).

In the exercise provided, a semantic error has caused the program to calculate bank interest annually instead of daily. This error does not stem from incorrect code structure or failed operations during runtime, but from a discrepancy between the intended logic and what's actually coded. The instructions are understood by the computer, yet they result in erroneous output because the program logic doesn't align with the intended task of computing daily interest.

Improving code to avoid semantic errors often entails thorough algorithm design and logic review, ensuring your code not only works but correctly implements the required functionality. Pseudo-code or flowcharts can be useful tools to map out the correct logic before diving into the actual coding.

Syntax Error

Syntax errors are the grammatical mistakes of programming; they occur when code does not conform to the rules of the programming language—like misspelling words or misplaced punctuation in a sentence.

For instance, forgetting a semicolon at the end of a statement in C++ or using an 'endif' instead of an 'end if' in Python could lead to syntax errors. The program will fail to compile or interpret, preventing it from running at all until these errors are corrected.

To minimize syntax errors, it's recommended to use an Integrated Development Environment (IDE) with syntax highlighting and code suggestions. Consistent code formatting and revision practices can also help catch these errors early on.

Runtime Error

Runtime errors sneak past the compiling stage but cause the program to crash or behave unexpectedly while running. Examples include dividing by zero, accessing out-of-bounds elements in an array, or running out of memory.

These errors are like unexpected potholes on a road; you only encounter them as you drive (or run the code). Detecting runtime errors often requires a combination of testing with different input scenarios and implementing error-handling code to gracefully manage unexpected states.

Good practices like input validation, using assertions, and comprehensive testing can significantly reduce the likelihood and impact of runtime errors. Exception handling mechanisms are key to constructing robust programs that can address these unexpected incidents without crashing.