PHP fgets Function
PHP fgets function tutorial shows how to read files line by line in PHP. Learn fgets with practical examples.
PHP fgets Function
last modified April 3, 2025
The PHP fgets function reads a line from a file pointer. It’s commonly used for reading files line by line in PHP applications.
Basic Definition
The fgets function reads up to length - 1 bytes from the file pointer. Reading stops when length - 1 bytes have been read, or a newline.
Syntax: fgets(resource $stream, ?int $length = null): string|false. The function returns the read string or false on failure.
Basic fgets Example
This shows the simplest usage of fgets to read a file line by line.
basic_fgets.php
<?php
declare(strict_types=1);
$file = fopen(“example.txt”, “r”);
if ($file) { while (($line = fgets($file)) !== false) { echo $line; } fclose($file); }
This opens “example.txt” and reads it line by line until EOF. Each line includes the newline character at the end. Always close files with fclose.
Reading Specific Length
The second parameter limits how many bytes to read from the line.
fgets_length.php
<?php
declare(strict_types=1);
$file = fopen(“example.txt”, “r”);
if ($file) { $line = fgets($file, 10); echo $line; fclose($file); }
This reads at most 9 bytes (10 - 1) from the first line. If the line is shorter, it stops at the newline. The length parameter is optional.
Reading CSV File
fgets can be combined with str_getcsv to parse CSV.
csv_reader.php
<?php
declare(strict_types=1);
$file = fopen(“data.csv”, “r”);
if ($file) { while (($line = fgets($file)) !== false) { $fields = str_getcsv($line); print_r($fields); } fclose($file); }
This reads a CSV file line by line and parses each line into an array of fields. The newline from fgets is handled by str_getcsv.
Error Handling
Proper error handling is important when working with file operations.
error_handling.php
<?php
declare(strict_types=1);
$filename = “nonexistent.txt”; $file = @fopen($filename, “r”);
if ($file === false) { echo “Failed to open file: $filename”; exit(1); }
while (($line = fgets($file)) !== false) { echo $line; }
fclose($file);
This shows proper error handling when opening files. The @ suppresses warnings, allowing custom error handling. Always check for false returns.
Reading Remote File
fgets can read from remote files when allow_url_fopen is enabled.
remote_file.php
<?php
declare(strict_types=1);
$url = “https://example.com/data.txt"; $file = fopen($url, “r”);
if ($file) { while (($line = fgets($file)) !== false) { echo htmlspecialchars($line); } fclose($file); }
This reads a remote file line by line. Note that htmlspecialchars protects against XSS when outputting remote content. Check PHP configuration.
Best Practices
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Resource Management: Always close files with fclose.
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Error Handling: Check for false returns from file operations.
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Memory Efficiency: Use fgets for large files.
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Security: Validate/sanitize file paths and content.
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Performance: Consider buffering for frequent small reads.
Source
This tutorial covered the PHP fgets function with practical examples showing its usage in different file reading scenarios.
Author
My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.
