Working with CSV in PHP: reading, writing, and data processing

Working with CSV in PHP: complete guide

CSV (Comma-Separated Values) is one of the most popular formats for exchanging tabular data. PHP has both built-in functions for working with CSV and powerful third-party libraries. In this article, we will cover all the main ways to read, write, and process CSV files in PHP.

Built-in PHP functions for working with CSV

PHP provides several built-in functions that allow you to work with CSV files without installing additional libraries. The main ones are:

• fgetcsv() — reading a line from a file and parsing it into an array
• fputcsv() — writing an array to a file in CSV format
• str_getcsv() — parsing a CSV string into an array

Reading a CSV file using fgetcsv

The fgetcsv() function reads one line from an open file and returns it as an array. Example of reading an entire file:

<?php$filename = 'data.csv';

if (($handle = fopen($filename, 'r')) !== false) {    while (($data = fgetcsv($handle, 1000, ',')) !== false) {        // $data — array with row data        echo implode(' | ', $data) . "";    }    fclose($handle);}?>

Parameters of the fgetcsv() function:

• handle — file handle
• length — maximum line length (usually 0 or 1000)
• separator — field delimiter (default is comma)
• enclosure — field enclosure character (default is double quote)
• escape — escape character (default is backslash)

Writing data to a CSV file

For writing, the fputcsv() function is used. It takes an array and converts it into a CSV string:

<?php$data = [    ['Name', 'Age', 'City'],    ['Ivan', 25, 'Moscow'],    ['Maria', 30, 'Saint Petersburg'],];

$filename = 'output.csv';$handle = fopen($filename, 'w');

foreach ($data as $row) {    fputcsv($handle, $row, ';', '"');}

fclose($handle);echo "File $filename successfully created!";?>

In this example, we use a semicolon (;) as the delimiter, which is common in Russian-language CSV files.

Processing large CSV files

When working with large files (hundreds of thousands of rows), it is important not to load the entire file into memory. Use line-by-line reading:

<?phpfunction processLargeCSV($filename) {    $handle = fopen($filename, 'r');        // Skip the header if present    $header = fgetcsv($handle);        while (($row = fgetcsv($handle)) !== false) {        // Process each row        $processed = array_map('trim', $row);        // Your processing logic goes here        yield $processed; // Use a generator    }        fclose($handle);}

// Usageforeach (processLargeCSV('bigdata.csv') as $row) {    // Work with each row individually    echo "Processed row: " . implode(',', $row) . "";}?>

Using generators (yield) allows you to process files of any size without memory overflow.

League\\Csv library for advanced work

For more complex tasks, it is recommended to use the league/csv library. It provides a convenient object-oriented interface and many additional features.

Installation via Composer:

composer require league/csv

Usage example:

<?phprequire 'vendor/autoload.php';

use League\\Csv\\Reader;use League\\Csv\\Writer;

// Reading CSV$csv = Reader::createFromPath('data.csv', 'r');$csv->setHeaderOffset(0); // First row is the header

// Getting all records as ass