PHP Comments: Single-Line, Multi-Line & Professional PHPDoc Standards

In professional software engineering, writing code that a computer understands is only half the battle; writing code that human teammates, graders, and your future self can understand is equally vital. Comments are non-executable explanatory notes written inside your PHP scripts. During script compilation, the PHP Zend Engine completely strips comments, ensuring zero performance overhead while maximizing code maintainability.

The Three Comment Formats in PHP

1. Single-Line Comments (//)

The double slash // instructs the PHP parser to ignore everything from the slashes to the end of the current line. It is the most common comment format for quick explanations:

<?php
    // Calculate total course fee including 18% GST
    $tuitionFee = 25000;
    $taxRate = 0.18; // In-line explanation of tax percentage
    $totalFee = $tuitionFee + ($tuitionFee * $taxRate);
?>

2. Unix Shell / Python Style Single-Line Comments (#)

PHP also supports the hash symbol #, originating from Unix shell scripts and Perl. It behaves identically to //:

<?php
    # Database connection parameters for local development
    $dbHost = "localhost";
    # $dbHost = "192.168.1.50"; # Temporarily disabled production IP
?>

3. Multi-Line Block Comments (/* ... */)

When an explanation spans multiple sentences, or when you want to temporarily disable a large block of debugging code, use multi-line comments:

<?php
    /*
      Author: Veewom Tutorial Studio
      Course: BCA Semester IV Advanced PHP
      Description: This module authenticates student portal credentials
      Last Updated: 2026
    */
    function authenticateStudent($rollNumber, $password) {
        // Authentication logic here...
    }
?>

Professional Standard: PHPDoc Documentation Blocks

In enterprise PHP projects and framework development (such as Laravel or Symfony), developers use PHPDoc. PHPDoc comments begin with /** (two asterisks) and utilize standardized tags to document function contracts:

<?php
/**
 * Calculates student semester grade and honors eligibility.
 *
 * @param string $studentId   The unique university roll number.
 * @param array  $subjectMarks Array of integer marks (0-100).
 * @param float  $attendancePercentage Attendance record from 0.0 to 100.0.
 *
 * @return string Returns "Honors", "Pass", or "Supplementary".
 * @throws InvalidArgumentException If marks array is empty.
 */
function evaluateSemesterResult(string $studentId, array $subjectMarks, float $attendancePercentage): string {
    if (empty($subjectMarks)) {
        throw new InvalidArgumentException("Marks array cannot be empty.");
    }

    $average = array_sum($subjectMarks) / count($subjectMarks);

    if ($average >= 80 && $attendancePercentage >= 75.0) {
        return "Honors";
    } elseif ($average >= 40) {
        return "Pass";
    }

    return "Supplementary";
}
?>

BCA / CS University Exam Corner

Interactive Student Practice Session