In PHP, what major types of runtime and compile time errors can be generated by the engine?

Introduction / Context:
Understanding PHP error types is essential for debugging and writing robust applications. Different error categories indicate different problems, such as syntax mistakes, missing functions, or non critical issues that the script can recover from. Interview questions often ask about error types to ensure that developers know how PHP reports problems and how script execution is affected by each category.

Given Data / Assumptions:

• PHP has a built in error handling system that classifies errors by severity.
• Typical categories include parse errors, fatal errors, warnings, and notices.
• Configuration settings such as error_reporting and display_errors control visibility of these errors.
• The question focuses on conceptual types, not numeric error codes.

Concept / Approach:
Parse errors occur at compile time when PHP interprets the script and finds invalid syntax, such as missing semicolons or incorrect parentheses. Fatal errors occur at runtime when PHP encounters a problem that it cannot recover from, such as calling an undefined function or running out of memory. Warnings are non fatal issues, like including a missing file with include(), where the script can continue but behaviour may be incorrect. Notices indicate minor problems such as using an undefined variable, which usually do not stop execution but can signal poor coding practices.

Step-by-Step Solution:
Step 1: Parse errors (compile time errors) are generated when PHP reads the script and detects invalid syntax before executing any code. These errors prevent the script from running at all until the syntax is corrected. Step 2: Fatal errors happen during execution when PHP reaches a state it cannot handle, for example trying to call a function that does not exist. Execution stops at the point of the fatal error. Step 3: Warnings signal problems that are serious but not fatal, such as an included file missing when using include(). PHP logs a warning and continues to execute the rest of the script, which may still produce output. Step 4: Notices inform developers of minor issues like reading an undefined variable or using an uninitialised index. The script continues running, but developers should fix these issues for clean code and predictable behaviour. Step 5: PHP also has other related levels such as strict standards messages and deprecated notices in older versions, but parse errors, fatal errors, warnings, and notices are the main categories. Step 6: This set of categories matches option a, which accurately summarises the major PHP error types.

Verification / Alternative check:
You can verify these categories by writing simple test scripts that deliberately cause different errors. A missing semicolon will produce a parse error. Calling an undefined function will cause a fatal error. Including a non existent file with include() will trigger a warning, while using an undefined variable will generate a notice if error reporting is configured to show it. Observing how each case affects script execution confirms the differences between these error types.

Why Other Options Are Wrong:
Option b is wrong because blue screen errors refer to operating system crashes, not PHP level error reporting. Option c is incorrect because PHP clearly distinguishes between syntax errors and runtime errors and has warnings and notices. Option d is wrong because PHP errors originate on the server side and are only sent to the browser as output or logs if configured.

Common Pitfalls:
A common pitfall is hiding errors in production by turning off error reporting completely, which can make troubleshooting much harder. A better approach is to log errors to files while displaying friendly messages to users. Another issue is ignoring notices and warnings, which can mask real bugs and lead to unpredictable behaviour. Developers should aim for code that runs cleanly with strict error_reporting settings in development, addressing parse errors, fatal errors, warnings, and notices promptly.

Final Answer:
PHP defines several major error types, including parse errors, fatal errors, warnings, and notices, each indicating a different severity level and having a different impact on whether the script can continue running.