Nested conditional execution in PHP - Mini Project: Build & Apply

Nested conditional execution

📖 Scenario: You are creating a simple PHP program to decide what message to show based on the weather and time of day.

🎯 Goal: Build a PHP script that uses nested if statements to check the weather and time, then prints the correct message.

📋 What You'll Learn

Create variables for $weather and $time with exact values

Add a variable $isWeekend to indicate if it is weekend

Use nested if statements to check $weather and $time

Print the correct message based on conditions

💡 Why This Matters

🌍 Real World

Nested conditions help programs make decisions based on multiple factors, like weather and time, similar to how apps show different messages or options.

💼 Career

Understanding nested conditional execution is essential for programming logic in web development, automation scripts, and many software applications.

1

DATA SETUP: Create weather and time variables

Create a variable called $weather and set it to the string "sunny". Also create a variable called $time and set it to the string "morning".

PHP

<?php

// Create variables $weather and $time with exact values
// Your code here

Hint

Use = to assign the string values to the variables.

2

CONFIGURATION: Add weekend indicator variable

Add a variable called $isWeekend and set it to true.

PHP

<?php

$weather = "sunny";
$time = "morning";

// Add variable $isWeekend and set it to true
// Your code here

Hint

Use true without quotes for boolean true.

3

CORE LOGIC: Use nested if statements to check conditions

Write nested if statements to check if $weather is "sunny". Inside that, check if $time is "morning". If both are true, set a variable $message to "Good morning! Enjoy the sunny day!". Otherwise, set $message to "Have a nice day!". If $weather is not "sunny", set $message to "Stay indoors and relax.".

PHP

<?php

$weather = "sunny";
$time = "morning";
$isWeekend = true;

// Use nested if statements to set $message based on $weather and $time
// Your code here

Hint

Use == to compare strings inside if conditions.

4

OUTPUT: Print the message

Write a print statement to display the value of the variable $message.

PHP

<?php

$weather = "sunny";
$time = "morning";
$isWeekend = true;

if ($weather == "sunny") {
    if ($time == "morning") {
        $message = "Good morning! Enjoy the sunny day!";
    } else {
        $message = "Have a nice day!";
    }
} else {
    $message = "Stay indoors and relax.";
}

// Print the message
// Your code here

Hint

Use print($message); to show the message.

Practice

1.

What does nested conditional execution mean in PHP?

easy

A. Running PHP code without any conditions

B. Writing multiple if statements one after another without nesting

C. Using only one if statement without any else

D. Using an if or else statement inside another if or else block

Solution

1. Step 1: Understand conditional statements

   Conditional statements like if and else let the program choose actions based on conditions.

2. Step 2: Define nested conditionals

   Nested conditionals mean placing one conditional inside another to check multiple conditions step-by-step.

3. Final Answer:

   Using an if or else statement inside another if or else block -> Option D

4. Quick Check:

   Nested conditionals = condition inside condition [OK]

Hint: Look for conditions placed inside other conditions [OK]

Common Mistakes:

• Thinking multiple separate ifs are nested
• Confusing nested with chained conditions
• Ignoring the inner condition placement

2.

Which of the following is the correct syntax for nested if statements in PHP?

<?php
if ($a > 0) {
    if ($b < 10) {
        echo "Inside nested if";
    }
}
?>

easy

A. Using elseif instead of nested if

B. Correct syntax with braces and proper nesting

C. Missing braces around inner if block

D. Using parentheses incorrectly around conditions

Solution

1. Step 1: Check braces usage

   Both outer and inner if statements have braces to define their blocks properly.

2. Step 2: Verify condition syntax

   Conditions use parentheses correctly and logical operators are valid.

3. Final Answer:

   Correct syntax with braces and proper nesting -> Option B

4. Quick Check:

   Proper braces and nesting = correct syntax [OK]

Hint: Always use braces {} for nested blocks [OK]

Common Mistakes:

• Omitting braces causing syntax errors
• Misplacing parentheses in conditions
• Confusing elseif with nested if

3.

What will be the output of the following PHP code?

<?php
$x = 5;
$y = 8;
if ($x > 3) {
    if ($y < 10) {
        echo "A";
    } else {
        echo "B";
    }
} else {
    echo "C";
}
?>

medium

A. No output

B. B

C. A

D. C

Solution

1. Step 1: Evaluate outer if condition

   $x = 5, which is greater than 3, so the outer if block runs.

2. Step 2: Evaluate inner if condition

   $y = 8, which is less than 10, so the inner if block runs and prints "A".

3. Final Answer:

   A -> Option C

4. Quick Check:

   5 > 3 and 8 < 10 = A [OK]

Hint: Check outer condition first, then inner [OK]

Common Mistakes:

• Ignoring inner condition result
• Confusing else blocks
• Assuming else runs when condition is true

4.

Find the error in this nested conditional PHP code:

<?php
$a = 10;
if ($a > 5)
    if ($a < 15)
        echo "Inside nested if";
    else
        echo "Outside nested if";
?>

medium

A. Missing braces causing else to pair with wrong if

B. Incorrect comparison operators

C. Echo statements missing semicolons

D. Variable $a not defined

Solution

1. Step 1: Analyze if-else pairing without braces

   Without braces, the else pairs with the nearest if, which is the inner one.

2. Step 2: Understand the problem

   This can cause confusion or unexpected behavior because the outer if has no else block explicitly.

3. Final Answer:

   Missing braces causing else to pair with wrong if -> Option A

4. Quick Check:

   Braces needed to clarify else pairing [OK]

Hint: Always use braces to avoid else ambiguity [OK]

Common Mistakes:

• Assuming else pairs with outer if
• Ignoring indentation as syntax guide
• Missing semicolons (not the issue here)

5.

Given the following PHP code, what will be the output?

<?php
$score = 75;
if ($score >= 90) {
    echo "Grade A";
} else {
    if ($score >= 75) {
        if ($score >= 80) {
            echo "Grade B+";
        } else {
            echo "Grade B";
        }
    } else {
        echo "Grade C";
    }
}
?>

hard

A. Grade B

B. Grade B+

C. Grade C

D. Grade A

Solution

1. Step 1: Check first condition

   $score = 75, which is not >= 90, so skip first if block.

2. Step 2: Check second condition

   $score >= 75 is true, so enter second if.

3. Step 3: Check nested condition inside second if

   $score >= 80 is false (75 < 80), so execute else and print "Grade B".

4. Final Answer:

   Grade B -> Option A

5. Quick Check:

   75 >= 75 but < 80 = Grade B [OK]

Hint: Follow conditions top-down carefully [OK]

Common Mistakes:

• Confusing >= 75 and >= 80 checks
• Skipping nested else block
• Assuming 75 is >= 80