File open modes in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file for reading only.

PHP

<?php
$file = fopen('example.txt', '[1]');
?>

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

Aw

Br

Ca

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' which opens the file for writing and truncates it.

The mode 'r' opens the file for reading only.

2fill in blank

medium

Complete the code to open a file for writing and truncate it if it exists.

PHP

<?php
$file = fopen('example.txt', '[1]');
?>

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

Aw

Br+

Ca

Dr

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'a' which appends instead of truncating.

The mode 'w' opens the file for writing and truncates it if it exists.

3fill in blank

hard

Fix the error in the code to open a file for appending.

PHP

<?php
$file = fopen('example.txt', '[1]');
?>

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

Aw

Br

Ca

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' which overwrites the file instead of appending.

The mode 'a' opens the file for appending, writing data at the end.

4fill in blank

hard

Fill both blanks to open a file for reading and writing without truncating.

PHP

<?php
$file = fopen('example.txt', '[1][2]');
?>

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

Ar

B+

Cw

Da

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w+' which truncates the file.

The mode 'r+' opens the file for reading and writing without truncating it.

5fill in blank

hard

Fill all three blanks to open a file for writing and reading, creating it if it doesn't exist.

PHP

<?php
$file = fopen('example.txt', '[1][2][3]');
?>

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

Ar

B+

Cw

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'r+' which does not create the file if missing.

The mode 'x+' opens the file for writing and reading, creates it if it doesn't exist.

Practice

1. Which PHP file open mode allows you to read from a file without changing its contents?

easy

A. r - Open for reading only

B. w - Open for writing only

C. a - Open for appending

D. x - Create and open for writing

Solution

1. Step 1: Understand the purpose of each mode

   r mode opens a file for reading only, without modifying it. Other modes allow writing or creating files.

2. Step 2: Match the mode to the requirement

   Since the question asks for reading without changing, r is the correct mode.

3. Final Answer:

   r - Open for reading only -> Option A

4. Quick Check:

   Read only = r [OK]

Hint: Read only mode is just 'r' in PHP file functions [OK]

Common Mistakes:

• Choosing 'w' which overwrites the file
• Confusing 'a' (append) with read mode
• Using 'x' which creates a new file

2. Which of the following is the correct syntax to open a file for writing in PHP?

easy

A. fopen('file.txt', 'r')

B. fopen('file.txt', 'a')

C. fopen('file.txt', 'rw')

D. fopen('file.txt', 'w')

Solution

1. Step 1: Recall the mode for writing

   The mode 'w' opens a file for writing and truncates it if it exists.

2. Step 2: Check syntax correctness

   fopen('file.txt', 'w') is the correct syntax to open for writing.

3. Final Answer:

   fopen('file.txt', 'w') -> Option D

4. Quick Check:

   Write mode = 'w' [OK]

Hint: Use 'w' to open file for writing in fopen [OK]

Common Mistakes:

• Using 'r' which is read-only
• Using 'rw' which is invalid in PHP
• Confusing 'a' (append) with write

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

$file = fopen('test.txt', 'a');
fwrite($file, "Hello\n");
fclose($file);
echo file_get_contents('test.txt');

medium

A. Hello

B. Empty output

C. Error: Cannot write to file

D. olleH

Solution

1. Step 1: Understand the 'a' mode effect

   Mode 'a' opens the file for appending, so "Hello\n" (string with actual newline) is added at the end.

2. Step 2: Check output of file_get_contents

   It reads the whole file content including the newline, and echo prints it with the newline interpreted.

3. Final Answer:

   Hello -> Option A

4. Quick Check:

   "Hello\n" adds a newline, so output is Hello followed by newline [OK]

Hint: Append adds 'Hello\n'; echo shows Hello with newline [OK]

Common Mistakes:

• Thinking '\n' becomes literal backslash-n
• Expecting 'Hello' without newline
• Assuming error without write permission

4. Identify the error in this PHP code snippet:

$file = fopen('data.txt', 'r');
fwrite($file, 'Test');
fclose($file);

medium

A. Missing file path

B. File not closed properly

C. Cannot write to a file opened in 'r' mode

D. fwrite syntax is incorrect

Solution

1. Step 1: Check file open mode

   The file is opened in 'r' mode which is read-only and does not allow writing.

2. Step 2: Understand fwrite limitation

   Calling fwrite on a read-only file causes an error because writing is not permitted.

3. Final Answer:

   Cannot write to a file opened in 'r' mode -> Option C

4. Quick Check:

   Write needs 'w' or 'a' mode [OK]

Hint: Write only works if file opened with 'w' or 'a' [OK]

Common Mistakes:

• Ignoring mode restrictions
• Assuming fclose fixes write errors
• Confusing syntax errors with mode errors

5. You want to open a file in PHP to read and write without truncating it, and create it if it doesn't exist. Which mode should you use?

hard

A. w+

B. a+

C. r+

D. x+

Solution

1. Step 1: Understand each mode's behavior

   r+ reads/writes but fails if file missing; w+ truncates file; a+ reads/writes, creates if missing, appends writes; x+ creates new file only.

2. Step 2: Match requirements

   We want read/write, no truncation, and create if missing. a+ fits all: it opens for reading and appending, creates file if missing, and does not truncate.

3. Final Answer:

   a+ -> Option B

4. Quick Check:

   Read/write + create + no truncate = a+ [OK]

Hint: Use 'a+' to read/write and create without truncating [OK]

Common Mistakes:

• Choosing 'r+' which fails if file missing
• Choosing 'w+' which truncates file
• Confusing 'x+' which fails if file exists