Assignment and compound assignment in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the value 10 to the variable $x.

PHP

<?php
$x [1] 10;
echo $x;

Drag options to blanks, or click blank then click option'

A=

B=>

C+=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '=' for assignment.

Using '=>' which is for arrays, not assignment.

The single equal sign = is used to assign a value to a variable in PHP.

2fill in blank

medium

Complete the code to add 5 to the variable $count using a compound assignment operator.

PHP

<?php
$count = 10;
$count [1] 5;
echo $count;

Drag options to blanks, or click blank then click option'

A-=

B=

C*=

D+=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' which replaces the value instead of adding.

Using '-=' or '*=' which subtract or multiply instead of add.

The += operator adds the right value to the variable and assigns the result back to it.

3fill in blank

hard

Fix the error in the code to multiply $num by 3 using a compound assignment operator.

PHP

<?php
$num = 4;
$num [1] 3;
echo $num;

Drag options to blanks, or click blank then click option'

A/=

B+=

C*=

D-=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+=' which adds instead of multiplies.

Using '/=' or '-=' which divide or subtract instead of multiply.

The *= operator multiplies the variable by the right value and assigns the result back.

4fill in blank

hard

Complete the code to subtract 2 from $value and then assign the result back to $value.

PHP

<?php
$value = 15;
$value [1] 2;
echo $value;

Drag options to blanks, or click blank then click option'

A-=

B+=

C;

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+=' which adds instead of subtracts.

Forgetting the semicolon at the end of the statement.

The -= operator subtracts and assigns. The semicolon ; ends the statement.

5fill in blank

hard

Fill both blanks to divide $total by 4, assign the result back, and then add 1.

PHP

<?php
$total = 20;
$total [1] 4;
$total [2] 1;
echo $total;

Drag options to blanks, or click blank then click option'

A/=

B;

C+=

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '/=' for division assignment.

Forgetting semicolons at the end of statements.

Using '+=' before dividing.

First, /= divides and assigns. Then the statement ends with ;. Next, += adds and assigns 1.

Practice

1. What does the += operator do in PHP?

easy

A. Assigns the right value to the left variable without any operation

B. Multiplies the left variable by the right value

C. Subtracts the right value from the left variable

D. Adds the right value to the left variable and assigns the result to the left variable

Solution

1. Step 1: Understand the += operator

   The += operator adds the value on the right to the variable on the left.

2. Step 2: Assign the result back to the left variable

   It updates the left variable with the new sum.

3. Final Answer:

   Adds the right value to the left variable and assigns the result to the left variable -> Option D

4. Quick Check:

   += means add and assign [OK]

Hint: Think: add right to left and save in left [OK]

Common Mistakes:

• Confusing += with simple assignment =
• Thinking it subtracts or multiplies
• Believing it only adds without assignment

2. Which of the following is the correct syntax to multiply a variable $x by 5 and update it in PHP?

easy

A. $x *= 5;

B. $x =* 5;

C. $x = *5;

D. $x = 5*;

Solution

1. Step 1: Identify the correct compound assignment syntax

   The correct syntax for multiplying and assigning is $x *= 5; with no spaces between * and =.

2. Step 2: Check other options for syntax errors

   The other options have incorrect placement of operators or missing operands.

3. Final Answer:

   $x *= 5; -> Option A

4. Quick Check:

   Use *= for multiply and assign [OK]

Hint: Remember no space: variable *= value [OK]

Common Mistakes:

• Writing =* instead of *= operator
• Adding spaces between * and =
• Placing * or = incorrectly

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

$a = 10;
$a += 5;
$a -= 3;
echo $a;

medium

A. 10

B. 12

C. 8

D. 15

Solution

1. Step 1: Calculate after first operation

   Initially, $a = 10. After $a += 5;, $a becomes 10 + 5 = 15.

2. Step 2: Calculate after second operation

   Then $a -= 3; subtracts 3: 15 - 3 = 12.

3. Final Answer:

   12 -> Option B

4. Quick Check:

   10 + 5 - 3 = 12 [OK]

Hint: Perform operations step-by-step from top to bottom [OK]

Common Mistakes:

• Ignoring the order of operations
• Adding instead of subtracting in second step
• Confusing initial value with final

4. Identify the error in the following PHP code:

$count = 5;
$count +== 3;
echo $count;

medium

A. Variable name is invalid

B. Missing semicolon after first line

C. Using +== instead of +=

D. echo statement syntax error

Solution

1. Step 1: Check the compound assignment operator

   The operator +== is invalid in PHP. The correct operator to add and assign is +=.

2. Step 2: Verify other parts of code

   Semicolons are present, variable name is valid, and echo syntax is correct.

3. Final Answer:

   Using +== instead of += -> Option C

4. Quick Check:

   Compound assignment must be +=, not +== [OK]

Hint: Remember compound operators have one = only [OK]

Common Mistakes:

• Typing two equal signs in compound assignment
• Confusing comparison (==) with assignment (=)
• Assuming +== is valid operator

5. Given the code below, what will be the value of $result after execution?

$x = 4;
$y = 3;
$result = 10;
$result += $x * $y;
$result -= 5;
$result /= 2;

hard

A. 8.5

B. 6.5

C. 10

D. 9

Solution

1. Step 1: Calculate multiplication and addition

   $x * $y = 4 * 3 = 12. Then $result += 12 means 10 + 12 = 22.

2. Step 2: Subtract 5 from $result

   22 - 5 = 17.

3. Step 3: Divide $result by 2

   17 / 2 = 8.5.

4. Step 4: Check options carefully

   8.5 is 8.5, but note the question asks for final value of $result after all operations.

5. Final Answer:

   8.5 -> Option A

6. Quick Check:

   (10 + 4*3 - 5) / 2 = 8.5 [OK]

Hint: Follow order: multiply, add, subtract, divide [OK]

Common Mistakes:

• Ignoring operator precedence
• Doing operations in wrong order
• Dividing before subtracting