Working with CSV in PHP: Reading, Writing, and Data…

Working with CSV in PHP: Reading, Writing, and Data Processing

The CSV (Comma-Separated Values) format remains one of the most popular ways to exchange tabular data. PHP provides built-in functions for working with this format, making it an ideal choice for data import/export, integration with CRM, accounting systems, and report generation. In this article, we will cover the complete CSV workflow: from opening a file to handling complex cases with escaping and encodings.

Core PHP Functions for Working with CSV

PHP has two key functions: fgetcsv() for reading and fputcsv() for writing. They automatically handle delimiters, quotes, and escaping.

Reading a CSV File Line by Line

A basic example of reading a CSV using fgetcsv():

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

if (($handle = fopen($filename, 'r')) !== false) {    // Read headers (first line)    $headers = fgetcsv($handle, 1000, ',');        if ($headers !== false) {        echo "Headers: " . implode(', ', $headers) . "<br>";                // Read data line by line        while (($row = fgetcsv($handle, 1000, ',')) !== false) {            echo "Row: " . implode(' | ', $row) . "<br>";        }    }        fclose($handle);}?>

Parameters of fgetcsv():

handle — file handle (result of fopen)
length — maximum line length (0 is recommended for automatic detection)
separator — field delimiter (comma by default)
enclosure — quote character (double quote by default)
escape — escape character (backslash by default)

Writing Data to CSV

The fputcsv() function automatically formats a line with proper escaping:

<?php$data = [    ['ID', 'Name', 'Email', 'Registration Date'],    [1, 'Ivan Petrov', 'ivan@example.com', '2024-01-15'],    [2, 'Maria Sidorova', 'maria@example.com', '2024-02-20'],    [3, 'Alexey "Professor" Ivanov', 'alex@example.com', '2024-03-10']];

$filename = 'users.csv';

if (($handle = fopen($filename, 'w')) !== false) {    // Write BOM for correct Cyrillic display in Excel    fwrite($handle, "\\xEF\\xBB\\xBF");        foreach ($data as $row) {        fputcsv($handle, $row, ';'); // Use semicolon for Excel    }        fclose($handle);    echo "File $filename successfully created!";}?>

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 streaming processing:

<?phpfunction processLargeCSV($filename, callable $callback) {    $handle = fopen($filename, 'r');    if ($handle === false) {        throw new Exception("Could not open file: $filename");    }        $headers = fgetcsv($handle, 0, ',');    if ($headers === false) {        fclose($handle);        throw new Exception("Empty file or error reading headers");    }        $rowNumber = 1;    while (($row = fgetcsv($handle, 0, ',')) !== false) {        if (count($row) !== count($headers)) {            // Skip rows with an incorrect number of fields            continue;        }                // Combine headers with data        $assocRow = array_combine($headers, $row);        call_user_func($callback, $assocRow, $rowNumber);        $rowNumber++;    }        fclose($handle);}

// Usage:processLargeCSV('bigdata.csv', function($row, $number) {    echo "Row #$number: {$row['email']} - {$row['name']}<br>";});?>