Print statement in PHP - Time & Space Complexity

Time Complexity: Print statement

O(n)

Understanding Time Complexity

Let's see how the time to run a simple print statement changes as we run it multiple times.

We want to know how the number of print commands affects the total work done.

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

<?php
for ($i = 0; $i < $n; $i++) {
    print("Hello\n");
}
?>
    

This code prints "Hello" a number of times equal to the input size $n.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The print statement inside the loop.
• How many times: It runs once for each number from 0 up to $n - 1, so $n times.

How Execution Grows With Input

Each time we increase $n, the print runs that many more times.

Input Size (n)	Approx. Operations
10	10 prints
100	100 prints
1000	1000 prints

Pattern observation: The number of print operations grows directly with the input size.

Final Time Complexity

Time Complexity: O(n)

This means if you double the input size, the print commands double too, so the work grows in a straight line with input.

Common Mistake

[X] Wrong: "The print statement takes the same time no matter how many times it runs."

[OK] Correct: Each print command takes some time, so more prints mean more total time. The total work grows with the number of prints.

Interview Connect

Understanding how simple loops affect time helps you explain how programs scale, a key skill in coding interviews and real projects.

Self-Check

"What if we replaced the print statement with a nested loop that also prints? How would the time complexity change?"

Practice

1. What does the print statement do in PHP?

easy

A. It shows text or values on the screen.

B. It saves data to a file.

C. It creates a new variable.

D. It deletes a file.

Solution

1. Step 1: Understand the purpose of print

   The print statement is used to display output on the screen in PHP.

2. Step 2: Compare options with print's function

   Only It shows text or values on the screen. correctly describes this behavior; others describe unrelated actions.

3. Final Answer:

   It shows text or values on the screen. -> Option A

4. Quick Check:

   Print = Show output [OK]

Hint: Print always outputs text or values to the screen [OK]

Common Mistakes:

• Thinking print saves or deletes files
• Confusing print with variable creation
• Assuming print modifies data silently

2. Which of the following is the correct syntax to print the text Hello World in PHP?

easy

A. print(Hello World);

B. print "Hello World";

C. print "Hello World"

D. print 'Hello World'

Solution

1. Step 1: Check for quotes around text

   Text must be inside quotes to be printed correctly in PHP.

2. Step 2: Check for semicolon at the end

   PHP statements must end with a semicolon; only print "Hello World"; has both quotes and semicolon.

3. Final Answer:

   print "Hello World"; -> Option B

4. Quick Check:

   Quotes + semicolon = correct print syntax [OK]

Hint: Text must be in quotes and end with semicolon [OK]

Common Mistakes:

• Omitting quotes around text
• Missing semicolon at the end
• Using parentheses without quotes

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

print 123;
print " apples";

medium

A. 123apples

B. 123" apples"

C. 123 apples

D. Error: missing semicolon

Solution

1. Step 1: Analyze first print statement

   print 123; prints the number 123 without quotes.

2. Step 2: Analyze second print statement

   print " apples"; prints the text ' apples' with a space before apples.

3. Step 3: Combine outputs

   Both prints run one after another, so output is '123 apples'.

4. Final Answer:

   123 apples -> Option C

5. Quick Check:

   Number + text prints together = 123 apples [OK]

Hint: Print numbers without quotes, text with quotes, outputs join [OK]

Common Mistakes:

• Expecting quotes to print literally
• Missing space between number and text
• Thinking missing semicolon causes error here

4. Identify the error in this PHP code:

print "Hello World"

medium

A. Missing semicolon at the end

B. Quotes should be single quotes

C. print should be uppercase

D. Missing parentheses around text

Solution

1. Step 1: Check statement ending

   PHP statements must end with a semicolon; this code misses it.

2. Step 2: Verify other syntax parts

   Quotes can be single or double, print is case-insensitive, parentheses optional.

3. Final Answer:

   Missing semicolon at the end -> Option A

4. Quick Check:

   Semicolon missing = syntax error [OK]

Hint: Always end print statements with a semicolon [OK]

Common Mistakes:

• Forgetting semicolon at line end
• Thinking print must be uppercase
• Adding unnecessary parentheses

5. How can you print the phrase PHP version: 8.1 using a single print statement with a variable $version = 8.1;?

hard

A. print "PHP version: $version";

B. print 'PHP version: $version';

C. print PHP version: $version;

D. print ("PHP version: " . $version);

Solution

1. Step 1: Understand variable interpolation in quotes

   Double quotes allow variables inside text to be replaced; single quotes do not.

2. Step 2: Check each option

   print "PHP version: $version"; would work but misses semicolon; print 'PHP version: $version'; prints variable name literally; print PHP version: $version; is syntax error; print ("PHP version: " . $version); concatenates string and variable correctly with semicolon.

3. Final Answer:

   print ("PHP version: " . $version); -> Option D

4. Quick Check:

   Concatenate string and variable with dot and semicolon [OK]

Hint: Use dot (.) to join strings and variables in print [OK]

Common Mistakes:

• Using single quotes with variables expecting interpolation
• Omitting semicolon
• Not concatenating strings and variables properly