PHP file_get_contents Function
last modified April 3, 2025
The PHP file_get_contents function reads entire file contents into
a string. It's a simple way to read files without manual file handling.
Basic Definition
The file_get_contents function reads a file and returns its contents
as a string. It can read local files and URLs when allow_url_fopen is enabled.
Syntax: file_get_contents(string $filename, bool $use_include_path = false,
resource $context = null, int $offset = 0, int $maxlen = null): string|false.
Basic file_get_contents Example
This shows the simplest usage of file_get_contents to read a file.
<?php
declare(strict_types=1);
$content = file_get_contents('data.txt');
if ($content !== false) {
echo $content;
} else {
echo "Failed to read file";
}
This reads the entire contents of 'data.txt' into a string. Always check the return value as it returns false on failure.
Reading Remote Content
file_get_contents can read remote files when allow_url_fopen is on.
<?php
declare(strict_types=1);
$url = 'https://example.com/data.json';
$content = file_get_contents($url);
if ($content !== false) {
$data = json_decode($content, true);
print_r($data);
} else {
echo "Failed to fetch remote content";
}
This fetches JSON data from a remote URL and decodes it. Note that remote requests may fail due to network issues or server restrictions.
Using Context Options
Context options allow customizing the file reading behavior.
<?php
declare(strict_types=1);
$opts = [
'http' => [
'method' => 'GET',
'header' => "User-Agent: MyCustomAgent\r\n"
]
];
$context = stream_context_create($opts);
$content = file_get_contents('https://example.com', false, $context);
if ($content !== false) {
echo substr($content, 0, 200);
}
This sets a custom User-Agent header for the HTTP request. Context options are useful for adding headers, timeouts, or other stream behaviors.
Reading Partial Content
The function can read a portion of a file using offset and maxlen parameters.
<?php
declare(strict_types=1);
$filename = 'large_file.log';
$content = file_get_contents($filename, false, null, 100, 50);
if ($content !== false) {
echo "Read 50 bytes starting at position 100:\n";
echo $content;
}
This reads 50 bytes starting from position 100 in the file. Partial reading is useful for large files where you only need specific portions.
Error Handling
Proper error handling is essential when working with file operations.
<?php
declare(strict_types=1);
$filename = 'nonexistent.txt';
try {
$content = file_get_contents($filename);
if ($content === false) {
throw new RuntimeException("Failed to read file");
}
echo $content;
} catch (RuntimeException $e) {
error_log($e->getMessage());
echo "Error: " . $e->getMessage();
}
This demonstrates proper error handling with exceptions. Always handle potential failures when working with file operations.
Best Practices
- Error Handling: Always check for false return value.
- Memory Usage: Avoid reading very large files entirely.
- Security: Validate input paths when reading files.
- Performance: Consider caching for frequently read files.
- Remote Content: Use proper timeouts for remote requests.
Source
PHP file_get_contents Documentation
This tutorial covered the PHP file_get_contents function with
practical examples showing its usage in different scenarios.