Reading files (fread, fgets, file) in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code using fread?

Consider this PHP code that reads from a file named example.txt containing the text Hello World!:

$file = fopen('example.txt', 'r');
$content = fread($file, 5);
fclose($file);
echo $content;

What will be printed?

PHP

$file = fopen('example.txt', 'r');
$content = fread($file, 5);
fclose($file);
echo $content;

A Hello World

B Hello World!

C Hello

D World

💡 Hint

Remember, fread reads a specific number of bytes from the file.

The fread function reads exactly 5 bytes from the file. Since the file contains "Hello World!", reading 5 bytes returns "Hello".

❓ Predict Output

intermediate

What does fgets() return when reading a file line?

Given a file data.txt with the content:

Line one
Line two
Line three

What will this PHP code output?

$file = fopen('data.txt', 'r');
$line = fgets($file);
fclose($file);
echo $line;

PHP

$file = fopen('data.txt', 'r');
$line = fgets($file);
fclose($file);
echo $line;

A Line one

B Line one\n

C Line one\r\n

D Line one\nLine two

💡 Hint

Check if fgets includes the newline character at the end of the line.

The fgets function reads a line including the newline character at the end. So it returns "Line one\n" (newline character included).

❓ Predict Output

advanced

What is the output of reading a file with file() function?

Assume notes.txt contains:

First line
Second line
Third line

What will this PHP code output?

$lines = file('notes.txt');
echo count($lines);

PHP

$lines = file('notes.txt');
echo count($lines);

A 3

B 1

C 0

D Error

💡 Hint

The file() function reads the file into an array, one element per line.

The file() function returns an array where each element is a line from the file. Since there are 3 lines, count($lines) returns 3.

❓ Predict Output

advanced

What error does this PHP code raise when reading a non-existent file?

What happens when running this PHP code?

$file = fopen('missing.txt', 'r');
fgets($file);

PHP

$file = fopen('missing.txt', 'r');
fgets($file);

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

B Fatal error: Call to undefined function fopen()

C NULL

D Empty string

💡 Hint

Check what happens if you try to open a file that does not exist in read mode.

Trying to open a non-existent file in read mode causes a warning from fopen indicating the file cannot be found.

🧠 Conceptual

expert

Which option correctly reads the entire file content into a string?

You want to read the entire content of story.txt into a single string variable in PHP. Which code snippet does this correctly?

A

$file = fopen('story.txt', 'r');
$content = '';
while (!feof($file)) {
  $content .= fgets($file);
}
fclose($file);
echo $content;

B

$content = file('story.txt');
echo $content;

C

$content = fread('story.txt');
echo $content;

D

$content = file_get_contents('story.txt');
echo $content;

💡 Hint

Look for the function that reads the whole file as a string in one call.

file_get_contents() reads the entire file content into a string. Option D reads line by line and concatenates, which works but is more complex. Option D returns an array, not a string. Option D is invalid because fread requires a file handle and length.