File open modes in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code when opening a file in 'r' mode?

Consider the following PHP code snippet. What will it output if the file 'example.txt' exists and contains the text 'Hello World'?

PHP

<?php
$handle = fopen('example.txt', 'r');
$content = fread($handle, 5);
echo $content;
fclose($handle);
?>

A World

B Error: Cannot open file

C Hello World

D Hello

💡 Hint

The 'r' mode opens the file for reading from the beginning.

The fread function reads 5 bytes from the file starting at the beginning, so it outputs 'Hello'.

❓ Predict Output

intermediate

What happens when opening a non-existent file in 'r' mode?

What will the following PHP code output if 'nofile.txt' does not exist?

PHP

<?php
$handle = fopen('nofile.txt', 'r');
if (!$handle) {
    echo 'Failed to open file';
} else {
    echo 'File opened';
}
?>

A File opened

B Failed to open file

C Warning: fopen(): failed to open stream: No such file or directory

D Empty output

💡 Hint

The 'r' mode requires the file to exist.

Opening a non-existent file in 'r' mode returns false, so the code prints 'Failed to open file'.

❓ Predict Output

advanced

What is the output when writing to a file opened in 'w' mode?

Given the file 'data.txt' contains 'Old Data', what will be the content of the file after running this PHP code?

PHP

<?php
$handle = fopen('data.txt', 'w');
fwrite($handle, 'New Data');
fclose($handle);
$contents = file_get_contents('data.txt');
echo $contents;
?>

A New Data

B Error: Cannot write to file

C Old DataNew Data

D Old Data

💡 Hint

The 'w' mode truncates the file before writing.

Opening a file in 'w' mode clears its contents, so after writing 'New Data', the file contains only that.

❓ Predict Output

advanced

What will be the output when appending to a file with 'a' mode?

If 'log.txt' initially contains 'Line1\n', what will be the content after running this PHP code?

PHP

<?php
$handle = fopen('log.txt', 'a');
fwrite($handle, 'Line2\n');
fclose($handle);
$contents = file_get_contents('log.txt');
echo $contents;
?>

A

Line1
Line2

B

Line2

C Line1

D Error: Cannot append to file

💡 Hint

The 'a' mode adds data to the end of the file without deleting existing content.

The 'a' mode appends 'Line2\n' after the existing 'Line1\n', so the file contains both lines.

🧠 Conceptual

expert

Which file open mode allows reading and writing without truncating the file?

In PHP, which file open mode lets you read and write to a file without deleting its existing content at open?

A 'x+'

B 'w+'

C 'r+'

D 'a+'

💡 Hint

One mode opens the file for reading and writing but does not clear it.

'r+' opens the file for reading and writing starting at the beginning without truncating the file. 'w+' truncates the file. 'a+' opens for reading and writing but places the pointer at the end for writing. 'x+' creates a new file and fails if it exists.