All 7 File Handling & File System Functions questions
More in File Handling & File System Functions
How do you write data to a file in PHP, and what is the difference between overwriting a file and appending to it? How do you check whether a file or directory exists, and how do you retrieve useful metadata like a file's size or last modified time? How do you work with directories in PHP, including listing their contents, creating new directories, and recursively deleting them? How do file locking mechanisms in PHP, using the flock function, help prevent data corruption when multiple processes might write to the same file concurrently? How do stream wrappers and stream contexts in PHP allow file functions to work seamlessly with non local resources like remote URLs or cloud storage? What security risks are associated with file handling operations that involve user supplied file paths, and how does path traversal attack prevention work?
Advertisement
PHP › File Handling & File System Functions

How do you read the contents of a file in PHP using functions like file_get_contents and fopen?

Beginner

Answer

file_get_contents provides a simple, convenient way to read an entire file's contents into a single string in one function call, which is perfect for smaller files, while fopen opens a file and returns a file handle that you can then read from incrementally using functions like fgets or fread, which is more appropriate for very large files where loading the entire content into memory at once would be impractical.
$content = file_get_contents('data.txt');

$handle = fopen('largefile.txt', 'r');
while (($line = fgets($handle)) !== false) {
    echo $line;
}
fclose($handle);
Real-world example A configuration loader uses file_get_contents to quickly read a small settings file into memory, while a log analysis tool uses fopen and fgets to process a massive multi gigabyte log file line by line without exhausting available memory.

Common follow-ups: What is the memory difference between file_get_contents and reading a file line by line?;What happens if you forget to close a file handle after opening it?

JSON Handling in PHP;Performance Optimization & OPcache
All 7 File Handling & File System Functions questions