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PHP File Open/Read

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Reading files is one of the fundamental tasks in PHP file handling. Whether you are displaying content from a text file, processing CSV data, or importing logs, understanding how to open and read files efficiently is essential.

This tutorial explains how to open files in different modes, read them fully or line by line, and handle errors gracefully, with practical examples.

Why File Reading Matters

When Vrinda is building a blog, she might store posts in text files. To display these posts on the website, she needs to read files efficiently. Similarly, Ananya could have a file containing a list of users, and reading the file is the first step in processing or displaying this information.

PHP provides multiple functions to read file content, including:

  • fopen() – to open a file

  • fread() – to read a specific number of bytes

  • fgets() – to read a file line by line

  • file() – to read an entire file into an array

  • file_get_contents() – to read an entire file into a string

Opening a File

Before reading a file, you must open it using fopen().

<?php
$file = fopen("example.txt", "r"); // open file in read-only mode
if ($file) {
    echo "File opened successfully.";
} else {
    echo "Unable to open file.";
}
?>

  • "r" mode opens the file for reading only.

  • If the file does not exist, PHP will return false.

Tip: Always check whether the file opened successfully to prevent errors.

Reading the Entire File with fread()

The fread() function allows you to read a specific number of bytes from a file.

<?php
$file = fopen("example.txt", "r");
$content = fread($file, filesize("example.txt")); // read full file
fclose($file);
echo $content;
?>

  • filesize() determines how many bytes to read.

  • Closing the file with fclose() frees up server resources.

If Riya writes a poem in example.txt, this code will read and display the entire poem.

Reading a File Line by Line with fgets()

Sometimes, reading a file line by line is more efficient, especially for large files.

<?php
$file = fopen("data.txt", "r");
if ($file) {
    while (!feof($file)) { // loop until the end of the file
        $line = fgets($file); // read one line at a time
        echo $line . "<br>";
    }
    fclose($file);
} else {
    echo "Failed to open file.";
}
?>

  • feof() checks whether the end of the file has been reached.

  • fgets() reads the file one line at a time.

For example, Ananya could have a list of student names stored line by line in data.txt. This loop will display each name neatly.

Reading a File into an Array with file()

The file() function reads the entire file into an array, where each line becomes an array element.

<?php
$lines = file("students.txt");
foreach ($lines as $line) {
    echo $line . "<br>";
}
?>

If Vrinda has a file with project titles, each title will be stored as a separate element, making it easy to loop through and display.

Reading a File into a String with file_get_contents()

The file_get_contents() function reads an entire file into a string. It is simpler than using fopen() and fread() for smaller files.

<?php
$content = file_get_contents("message.txt");
echo $content;
?>

  • Ideal for quickly reading small text files.

  • Returns false if the file cannot be opened.

If Riya has a file message.txt with a welcome note, this function will display it in one step.

Handling Errors Gracefully

Always handle errors when opening or reading files.

<?php
$file = @fopen("missing.txt", "r") or die("File not found!");
?>

  • The @ suppresses warnings.

  • die() displays a custom error message and stops execution.

This prevents the page from crashing if a file is missing or inaccessible.

Example: Reading User Feedback from a File

Suppose Ananya wants to display all user feedback stored in feedback.txt.

<?php
$file = fopen("feedback.txt", "r");
if ($file) {
    while (!feof($file)) {
        $feedback = fgets($file);
        echo "<p>$feedback</p>";
    }
    fclose($file);
} else {
    echo "No feedback available.";
}
?>

  • Each line of the file represents a separate feedback entry.

  • Displaying it in <p> tags improves readability on a webpage.

Example: Counting Lines in a File

If Vrinda wants to know how many entries are in her file:

<?php
$lines = file("feedback.txt");
echo "There are " . count($lines) . " feedback entries.";
?>

This method is efficient and easy to implement for small to medium-sized files.

Best Practices for File Reading

  1. Always close files using fclose() after reading.

  2. Check if files exist with file_exists() before opening.

  3. Handle large files line by line with fgets() to avoid memory overload.

  4. Use proper permissions to ensure files are readable but secure.

  5. Sanitize output if the file contains user-submitted content to prevent XSS attacks.

Summary of the Tutorial

PHP makes reading files straightforward with multiple options:

  • fopen() and fread() for full control over file reading

  • fgets() to read line by line

  • file() to read into an array

  • file_get_contents() to read the whole file as a string

Whether you’re displaying text, logs, or user data, these functions let you read and process files efficiently and securely.

Practice Questions

  1. Open a file named example.txt in read mode and display its full content.

  2. Read a file line by line using fgets() and display each line on a new HTML line.

  3. Use file_get_contents() to read the entire content of message.txt and echo it.

  4. Read a file into an array using file() and loop through it to display each element.

  5. Check if a file named data.txt exists before attempting to open it.

  6. Handle errors gracefully when opening a file that may not exist using @fopen() and die().

  7. Count the number of lines in a file named feedback.txt and display the count.

  8. Display all user feedback from feedback.txt, with each feedback entry inside a <p> tag.

  9. Read a large file line by line and stop reading after 10 lines.

  10. Open a file, read its content, and then close it using fclose() to free server resources.

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