12.5.3.5 describe a syntax error in a programming
12.5.3.1 describe run-time errors in a programming 
12.5.3.6 describe a logic error in a programming

Types of programming errors

Errors are the mistakes or faults in the program that cause our program to behave unexpectedly and it is no doubt that well-versed and experienced programmers also make mistakes. Programming errors are generally known as Bugs and the process to remove bugs from the program is called Debug/Debugging.

There are basically three types of error:

1. Syntax error or Compilation error
2. Run-time error or Execution error
3. Logical error

Syntax error or Compilation error
Compilation errors are the most common error occurred due to typing mistakes or if you don't follow the proper syntax of the specific programming language. These errors are most common to beginners. These errors are thrown by the compilers and will prevent your program from running. It is also called a Compile time error or Syntax error. The compiler highlights the error by pointing to the line of the program and displays a description of each error, so these errors are easy to debug.

Example:

• misspelling a statement, eg writing iput instead of input
• missing brackets, eg opening a bracket, but not closing it
• missing semicolon
• errors in the sequence of expressions

Run-time error (Execution error)
Run-time errors are generated when the program is running and lead to abnormal behavior or termination of the program. The general cause of run-time errors is that your program is trying to perform an operation that is impossible to carry out.

Example:

• Dividing any number by zero,
• Accessing any file that doesn't exist,
• Negative value under a square root,
• Calling invalid functions,
• Not handling certain input correctly (ex. not appropriate data type),
• Out of bounds of array indices.

Logical error
The logical error will cause your program to perform undesired operations that you didn't intend your program to perform. These errors occur generally due to improper logic used in the program. These types of errors are difficult to debug.

Examples:

• errors in the performed computation, eg. using multiplication (a * b)  instead of adding (a + b)
• errors in the performed condition, eg. using "<" instead of "<="
• unintentionally creating a situation where an infinite loop may occur
• incorrectly using brackets in calculations
• unintentionally using the same variable name at different points in the program for different purposes.

Table for comparison of types of errors

Type of error	Compilation	Execution	Result
Syntax error
Run-time error
Logic error

Source: codeforwin.org

Questions:

1. Explain what is a programming error.

2. Describe the term "syntax error".

3. Explain the difference between run-time error and logic error.

Exercises:

Ex. 1

Ex. 2

Writing error-free code test questions

Ex. 3

Find logic errors

Exam questions: