PHP String Functions
strpos · str_contains · str_replace · substr · explode

<?php
$str = "Hello PHP World";
// 0123456789...

echo strpos($str, "PHP"); // 6 (P की position)
echo strpos($str, "World"); // 10
echo strpos($str, "Hello"); // 0 (पहली position!)
echo strpos($str, "Java"); // false (नहीं मिला)

// Case Sensitive — php !== PHP
echo strpos($str, "php"); // false (lowercase नहीं मिलेगा)
echo stripos($str, "php"); // 6 (stripos = case insensitive)

// Offset — किस position से search शुरू करें
$str2 = "cat and cat and cat";
echo strpos($str2, "cat"); // 0 (पहली)
echo strpos($str2, "cat", 1); // 8 (दूसरी)
echo strpos($str2, "cat", 9); // 16 (तीसरी)
?>

<?php
// 1. Email में @ है या नहीं
$email = "rahul@gmail.com";
if (strpos($email, "@") !== false) {
  echo "✅ Email valid लग रहा है";
}

// 2. URL में protocol check
$url = "https://hindinotespoint.com";
if (strpos($url, "https") === 0) {
  echo "✅ Secure HTTPS URL";
}

// 3. @ से पहले username निकालना
$pos = strpos($email, "@");
$username = substr($email, 0, $pos);
echo $username; // rahul

// 4. Spam word check
$comment = "Buy cheap medicine now!";
$spamWords = ["cheap", "buy now", "free money"];
foreach ($spamWords as $word) {
  if (stripos($comment, $word) !== false) {
    echo "❌ Spam detected: " . $word;
  }
}
?>

<?php
$str = "Hello PHP World";

var_dump(str_contains($str, "PHP")); // bool(true)
var_dump(str_contains($str, "Java")); // bool(false)
var_dump(str_contains($str, "php")); // bool(false) — case sensitive
var_dump(str_contains($str, "")); // bool(true) — empty string always true
?>

<?php
$url = "https://hindinotespoint.com/php/strings";
$file = "profile_photo.jpg";

// str_contains — कहीं भी है?
if (str_contains($url, "hindinotespoint")) {
  echo "✅ Internal link है";
}

// str_starts_with — शुरू में है?
if (str_starts_with($url, "https")) {
  echo "✅ Secure URL";
}

// str_ends_with — अंत में है?
if (str_ends_with($file, ".jpg")) {
  echo "✅ Valid image file";
}

// Multiple extensions check
$allowed = ['.jpg', '.jpeg', '.png', '.gif'];
$isValid = false;
foreach ($allowed as $ext) {
  if (str_ends_with(strtolower($file), $ext)) {
    $isValid = true;
    break;
  }
}
echo $isValid ? "✅ Valid image" : "❌ Invalid file";
?>

<?php
// Basic replace
echo str_replace("World", "PHP", "Hello World");
// Hello PHP

// Case insensitive — str_ireplace
echo str_ireplace("WORLD", "PHP", "Hello World");
// Hello PHP (WORLD को भी match करेगा)

// Array से multiple replace एक साथ
$search = ["Delhi", "Mumbai", "Chennai"];
$replace = ["New Delhi", "Mumbai City", "Madras"];
$text = "Delhi और Mumbai बड़े शहर हैं";
echo str_replace($search, $replace, $text);
// New Delhi और Mumbai City बड़े शहर हैं

// Replace delete — empty string से replace
$dirty = "Hello<script>alert('xss')</script> World";
echo str_replace(["<script>", "</script>"], "", $dirty);
// Hello alert('xss') World

// $count — कितनी बार replace हुआ
$count = 0;
str_replace("a", "@", "banana", $count);
echo $count; // 3
?>

<?php
// 1. URL-friendly slug बनाना
$title = "PHP Tutorial in Hindi 2025";
$slug = strtolower(str_replace(" ", "-", trim($title)));
echo $slug; // php-tutorial-in-hindi-2025

// 2. Email template — placeholder replace
$template = "Dear {NAME}, आपका order {ORDER_ID} ship हो गया।";
$email = str_replace(
  ['{NAME}', '{ORDER_ID}'],
  ['Rahul', 'ORD-2025-001'],
  $template
);
echo $email;
// Dear Rahul, आपका order ORD-2025-001 ship हो गया।

// 3. Phone number format करना
$phone = "98-765-43210";
$clean = str_replace(["-", " ", "(", ")"], "", $phone);
echo $clean; // 9876543210
?>

<?php
$str = "HindiNotes";
// H i n d i N o t e s
// 0 1 2 3 4 5 6 7 8 9 (forward)
// -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 (backward)

echo substr($str, 0, 5); // Hindi (0 से 5 chars)
echo substr($str, 5); // Notes (5 से end तक)
echo substr($str, 5, 3); // Not (5 से 3 chars)
echo substr($str, -5); // Notes (आखिरी 5 chars)
echo substr($str, -5, 3); // Not (आखिरी 5 से 3 chars)
echo substr($str, 2, -2); // ndiNot (2 से, आखिरी 2 छोड़ो)
?>

<?php
// 1. Blog content preview
$content = "PHP एक बहुत powerful server-side language है जो web development के लिए use होती है।";
$preview = strlen($content) > 40
  ? substr($content, 0, 40) . "..."
  : $content;
echo $preview;

// 2. Credit card masking
$card = "4111111111111234";
$last4 = substr($card, -4);
$masked = "XXXX-XXXX-XXXX-" . $last4;
echo $masked; // XXXX-XXXX-XXXX-1234

// 3. File extension निकालना
$file = "document.pdf";
$dotPos = strrpos($file, ".");
$extension = substr($file, $dotPos + 1);
echo $extension; // pdf

// 4. Name initials बनाना
$first = "Rahul";
$last = "Kumar";
$initials = substr($first, 0, 1) . substr($last, 0, 1);
echo strtoupper($initials); // RK
?>

<?php
// Comma से split
$fruits = explode(",", "Apple,Mango,Banana,Orange");
print_r($fruits);
// Array ( [0] => Apple [1] => Mango [2] => Banana [3] => Orange )

// Space से split
$words = explode(" ", "Hello PHP World");
echo $words[0]; // Hello
echo $words[1]; // PHP
echo $words[2]; // World

// $limit — max 2 pieces चाहिए
$parts = explode(",", "a,b,c,d,e", 3);
print_r($parts);
// Array ( [0] => a [1] => b [2] => c,d,e )
?>

<?php
// 1. CSV data process करना
$csvLine = "Rahul,25,Delhi,Developer";
$data = explode(",", $csvLine);
echo "नाम: " . $data[0]; // Rahul
echo "उम्र: " . $data[1]; // 25
echo "शहर: " . $data[2]; // Delhi
echo "काम: " . $data[3]; // Developer

// 2. Date split करना
$date = "2025-12-25";
[$year, $month, $day] = explode("-", $date); // Destructuring
echo "Year: $year, Month: $month, Day: $day";

// 3. Tags process करना
$tagStr = "PHP, Laravel, MySQL, HTML, CSS";
$tags = explode(", ", $tagStr);
foreach ($tags as $tag) {
  echo "<span class='tag'>" . trim($tag) . "</span>";
}

// 4. URL path segments
$path = "php/strings/functions";
$segments = explode("/", $path);
echo "Section: " . $segments[0]; // php
echo "Page: " . $segments[2]; // functions

// 5. implode — वापस जोड़ना (explode का opposite)
$joined = implode(" | ", $tags);
echo $joined; // PHP | Laravel | MySQL | HTML | CSS
?>

<?php
// Raw user input
$rawTitle = " How To Learn PHP in 2025 ";
$rawContent = "PHP एक popular language है। यह web development के लिए बहुत अच्छी है। इसे सीखना easy है।";
$rawTags = "PHP, Web Development, Tutorial, Hindi, Beginner";

// Step 1: Title clean करो (trim से)
$title = trim($rawTitle); // "How To Learn PHP in 2025"

// Step 2: URL slug बनाओ (str_replace से)
$slug = strtolower(str_replace(" ", "-", $title));
// "how-to-learn-php-in-2025"

// Step 3: Content preview बनाओ (substr से)
$preview = substr($rawContent, 0, 50) . "...";
// "PHP एक popular language है। यह web developm..."

// Step 4: Tags array बनाओ (explode से)
$tagsArr = explode(", ", $rawTags);
// ["PHP", "Web Development", "Tutorial", "Hindi", "Beginner"]

// Step 5: "PHP" tag है या नहीं check करो
if (str_contains($rawTags, "PHP")) {
  echo "✅ PHP category में add होगा";
}

// Step 6: Tags में "Tutorial" की position ढूँढो
$tutPos = array_search("Tutorial", $tagsArr);
echo "Tutorial tag index: " . $tutPos; // 2

// Step 7: Display
echo "Title: $title";
echo "Slug: $slug";
echo "Preview: $preview";
echo "Tags: " . implode(" | ", $tagsArr);
?>