Generator function execution model in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a generator function in PHP?

A generator function is a special function that can pause its execution and return values one at a time using the yield keyword, instead of returning all values at once.

beginner

How does the yield keyword affect the execution of a generator function?

The yield keyword pauses the function's execution and sends a value back to the caller. When the generator resumes, it continues from where it left off.

intermediate

What happens when a generator function is called in PHP?

Calling a generator function returns a Generator object immediately without running the function body. The function body runs only when iterating over the generator.

intermediate

Explain the difference between return and yield in a generator function.

return ends the generator and optionally sends a final value. yield pauses the generator and sends a value but allows resuming later to produce more values.

beginner

What is the benefit of using a generator function over returning an array?

Generators use less memory because they produce values one at a time on demand, instead of creating and storing the entire array in memory.

What does a generator function return when called in PHP?

A A Generator object

B An array of values

C The first yielded value

D Null

Calling a generator function returns a Generator object immediately without running the function body.

Which keyword is used to pause a generator function and send a value back?

A yield

B return

C break

D continue

The yield keyword pauses the generator and sends a value back to the caller.

What happens when the generator resumes after a yield?

A It restarts from the beginning

B It ends immediately

C It continues execution from the next statement after yield

D It throws an error

The generator resumes execution from the statement immediately after the yield.

Which of these is a key advantage of generators?

A Faster execution than normal functions always

B Lower memory usage by producing values on demand

C They can only return one value

D They automatically cache all results

Generators produce values one at a time, saving memory compared to building large arrays.

What does the return statement do inside a generator function?

A Skips the next yield

B Pauses the generator and sends a value

C Restarts the generator

D Ends the generator and optionally sends a final value

Return ends the generator function and can send a final value to the caller.

Describe how a generator function executes in PHP from the moment it is called until it finishes.

Think about the lifecycle of the generator and how yield controls execution.

Explain why using a generator function can be more memory efficient than returning an array.

Compare storing all data at once versus producing it step-by-step.