Switch statement execution in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of switch with fall-through

What is the output of this PHP code?

PHP

<?php
$val = 2;
switch ($val) {
    case 1:
        echo "One ";
    case 2:
        echo "Two ";
    case 3:
        echo "Three ";
        break;
    default:
        echo "Default ";
}
?>

A One Two Three

B Two Three

C Two

D Default

💡 Hint

Remember that without break, cases fall through to the next.

The switch starts at case 2, prints 'Two ', then falls through to case 3 and prints 'Three ', then breaks.

❓ Predict Output

intermediate

Switch with strict type comparison

What will this PHP code output?

PHP

<?php
$value = '5';
switch ($value) {
    case 5:
        echo "Number 5";
        break;
    case '5':
        echo "String 5";
        break;
    default:
        echo "No match";
}
?>

A Number 5

B String 5

C No match

D Error

💡 Hint

PHP switch uses loose comparison (==), not strict (===).

The string '5' loosely equals the integer 5, so case 5 matches first and prints 'Number 5'.

🔧 Debug

advanced

Identify the error in switch syntax

Which option contains a syntax error in the switch statement?

A

<?php
switch ($x) {
    case 1:
        echo "One";
        break;
    default
        echo "Default";
}
?>

B

<?php
switch ($x) {
    case 1:
        echo "One";
        break;
    default:
        echo "Default";
}
?>

C

<?php
switch ($x) {
    case 1:
        echo "One";
        break;
    case 2:
        echo "Two";
        break;
}
?>

D

<?php
switch ($x) {
    case 1:
        echo "One";
        break;
    case 2:
        echo "Two";
        break;
    default:
        echo "Default";
}
?>

💡 Hint

Check the syntax for the default case.

Option A misses the colon ':' after 'default', causing a syntax error.

❓ Predict Output

advanced

Switch with multiple cases and no breaks

What is the output of this PHP code?

PHP

<?php
$val = 1;
switch ($val) {
    case 0:
    case 1:
    case 2:
        echo "Low ";
    case 3:
        echo "Mid ";
        break;
    default:
        echo "High ";
}
?>

A Mid

B Low

C Low Mid

D High

💡 Hint

Cases 0,1,2 share the same block without breaks.

Value 1 matches case 1, prints 'Low ', then falls through to case 3 and prints 'Mid ', then breaks.

🧠 Conceptual

expert

Behavior of switch with non-scalar expression

What happens when you use an array as the switch expression in PHP like this?

PHP

<?php
$arr = [1, 2];
switch ($arr) {
    case [1, 2]:
        echo "Match";
        break;
    default:
        echo "No match";
}
?>

A Outputs 'Match' because arrays are compared by value.

B Outputs 'No match' because switch cannot compare arrays.

C Causes a fatal error due to invalid switch expression.

D Raises a warning and outputs 'No match'.

💡 Hint

PHP switch uses loose comparison but arrays in switch cause warnings.

Using arrays in switch causes a warning: 'Warning: Switch statement with non-scalar expression', then default runs printing 'No match'.

Practice

1. What does a switch statement do in PHP?

easy

A. It chooses which code to run based on a value.

B. It repeats code multiple times.

C. It defines a function.

D. It creates a new variable.

Solution

1. Step 1: Understand the purpose of switch

   A switch statement compares a value to multiple cases to decide which code block to run.

2. Step 2: Compare with other options

   Repeating code is done by loops, functions define reusable code, and variables store data, so these are not correct.

3. Final Answer:

   It chooses which code to run based on a value. -> Option A

4. Quick Check:

   Switch selects code by value = A [OK]

Hint: Switch picks code by matching value quickly [OK]

Common Mistakes:

• Confusing switch with loops
• Thinking switch defines functions
• Believing switch creates variables

2. Which of the following is the correct syntax to start a switch statement in PHP?

easy

A. switch [variable] {

B. switch variable {

C. switch (variable) {

D. switch variable() {

Solution

1. Step 1: Recall switch syntax

   In PHP, switch requires parentheses around the variable: switch (variable) {

2. Step 2: Check other options

   Options without parentheses or with brackets or parentheses after variable name are invalid syntax.

3. Final Answer:

   switch (variable) { -> Option C

4. Quick Check:

   Switch uses parentheses around variable [OK]

Hint: Switch always uses parentheses around the variable [OK]

Common Mistakes:

• Omitting parentheses
• Using square brackets instead of parentheses
• Adding parentheses after variable name

3. What will be the output of this PHP code?

 $color = 'red';
 switch ($color) {
   case 'blue':
     echo 'Blue color';
     break;
   case 'red':
     echo 'Red color';
     break;
   default:
     echo 'No color';
 }

medium

A. Blue color

B. Syntax error

C. No color

D. Red color

Solution

1. Step 1: Check the value of $color

   $color is set to 'red'.

2. Step 2: Match cases in switch

   The switch checks 'blue' first (no match), then 'red' (match), so it runs echo 'Red color' and breaks.

3. Final Answer:

   Red color -> Option D

4. Quick Check:

   Value 'red' matches case 'red' [OK]

Hint: Match value to case, break stops further checks [OK]

Common Mistakes:

• Forgetting break causes fall-through
• Assuming default runs even if case matches
• Mixing case values

4. Identify the error in this PHP switch code:

 $day = 3;
 switch ($day) {
   case 1:
     echo 'Monday';
   case 2:
     echo 'Tuesday';
     break;
   default:
     echo 'Other day';
 }

medium

A. Missing break after case 1 causes fall-through.

B. Switch statement syntax is incorrect.

C. Variable $day is not defined.

D. Default case should be first.

Solution

1. Step 1: Check breaks in cases

   Case 1 has no break, so if matched, it falls through to case 2.

2. Step 2: Understand effect of missing break

   Missing break causes code for case 2 to run even if case 1 matches, which is usually unintended.

3. Final Answer:

   Missing break after case 1 causes fall-through. -> Option A

4. Quick Check:

   Break missing after case 1 causes fall-through [OK]

Hint: Always add break after each case to avoid fall-through [OK]

Common Mistakes:

• Ignoring missing break causes multiple cases to run
• Thinking default must be first
• Assuming variable is undefined

5. Given this PHP code, what will be the output?

 $score = 85;
 switch (true) {
   case ($score >= 90):
     echo 'Grade A';
     break;
   case ($score >= 80):
     echo 'Grade B';
     break;
   case ($score >= 70):
     echo 'Grade C';
     break;
   default:
     echo 'Fail';
 }

hard

A. Grade A

B. Grade B

C. Grade C

D. Fail

Solution

1. Step 1: Understand switch(true) usage

   The switch compares true to each case condition result.

2. Step 2: Evaluate each case condition

   $score is 85, so ($score >= 90) is false, ($score >= 80) is true, so it matches case 2 and prints 'Grade B'.

3. Final Answer:

   Grade B -> Option B

4. Quick Check:

   Switch(true) matches first true case = Grade B [OK]

Hint: Use switch(true) to check conditions in order [OK]

Common Mistakes:

• Expecting switch to compare values directly
• Not understanding switch(true) trick
• Missing break causing fall-through