Parameter passing mechanisms in Compiler Design - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Call-by-Value

Which statement best describes the call-by-value parameter passing mechanism?

A The function receives a copy of the argument's value; changes inside the function do not affect the original variable.

B The function receives the memory address of the argument; changes inside the function affect the original variable.

C The function receives a reference to the argument; changes inside the function affect the original variable only if explicitly returned.

D The function receives a copy of the argument's value and a reference to the original variable simultaneously.

💡 Hint

Think about whether changes inside the function affect the original variable.

In call-by-value, the function works with a copy of the argument's value. Any changes inside the function do not affect the original variable outside.

📋 Factual

intermediate

Identifying Call-by-Reference Behavior

In which parameter passing mechanism does the called function directly modify the caller's variable?

A Call-by-reference

B Call-by-name

C Call-by-constant

D Call-by-value

💡 Hint

Consider which method allows the function to change the original variable.

Call-by-reference passes the variable's address or reference, allowing the function to modify the original variable directly.

🔍 Analysis

advanced

Comparing Call-by-Name and Call-by-Value

Consider the following code snippet in a language supporting call-by-name:

function f(x) { return x + x; }
f(3 + 4)

What is the difference in evaluation between call-by-name and call-by-value for the argument 3 + 4?

A Both evaluate <code>3 + 4</code> once before the call.

B Call-by-value evaluates <code>3 + 4</code> twice; call-by-name evaluates it once before the call.

C Call-by-value evaluates <code>3 + 4</code> once before the call; call-by-name evaluates <code>3 + 4</code> twice inside the function.

D Both evaluate <code>3 + 4</code> twice inside the function.

💡 Hint

Think about when the argument expression is evaluated in each mechanism.

Call-by-value evaluates the argument once before the function call, passing the value. Call-by-name delays evaluation until each use inside the function, so 3 + 4 is evaluated twice.

❓ Reasoning

advanced

Effect of Call-by-Result on Variable Values

In the call-by-result parameter passing mechanism, what happens to the variable passed as an argument after the function finishes execution?

A The variable remains unchanged regardless of the function's operations.

B The variable is updated with the final value computed inside the function.

C The variable is updated before the function starts execution and remains fixed during the function.

D The variable is updated only if the function explicitly returns it.

💡 Hint

Consider when the variable's value is copied back to the caller.

Call-by-result copies the value back to the caller's variable only after the function finishes, reflecting the final computed value.

❓ Comparison

expert

Distinguishing Call-by-Value-Result from Call-by-Reference

Which of the following statements correctly distinguishes call-by-value-result (copy-in copy-out) from call-by-reference?

A Call-by-value-result and call-by-reference are identical in behavior and timing of updates.

B Call-by-value-result passes the address of the variable; call-by-reference passes a copy of the value.

C Call-by-value-result evaluates the argument expression multiple times; call-by-reference evaluates it once.

D Call-by-value-result copies the argument value in and out, so changes inside the function do not affect the caller until the function ends; call-by-reference allows immediate changes to the caller's variable.

💡 Hint

Think about when the caller's variable is updated in each mechanism.

Call-by-value-result copies the argument value into the function and copies it back after the function finishes, so changes are not visible during execution. Call-by-reference passes the variable's address, so changes are immediate.