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PHP Strings

Strings are one of the most commonly used data types in PHP.

A string is a sequence of characters.

Examples:

$name = "Aayan";
$server = "ZyroNetwork";
$message = "Welcome to the server!";

Why Strings Matter

Strings are used everywhere:

✅ Player Names

✅ Chat Messages

✅ Commands

✅ Configurations

✅ JSON APIs

✅ Database Records

✅ Discord Bots

✅ PocketMine Plugins

Creating Strings

PHP provides two primary ways.

Double Quotes

$name = "Aayan";

Single Quotes

$name = 'Aayan';

Difference

Double quotes support variable interpolation.

Example:

$name = "Aayan";

echo "Hello $name";

Output:

Hello Aayan

Single quotes do NOT.

echo 'Hello $name';

Output:

Hello $name

String Length

Use:

strlen()

Example:

echo strlen("Zyro");

Output:

4

Unicode Strings

echo strlen("नमस्ते");

May produce unexpected results because PHP counts bytes.

Use:

mb_strlen()

Example:

echo mb_strlen("नमस्ते");

Concatenation

Strings can be joined using:

.

Example:

$name = "Aayan";

echo "Hello " . $name;

Output:

Hello Aayan

Concatenation Assignment

$message = "Hello";

$message .= " World";

Output:

Hello World

Escape Characters

New Line​

echo "Hello\nWorld";

Tab​

echo "Hello\tWorld";

Double Quote​

echo "\"Hello\"";

Backslash​

echo "\\";

Heredoc

Useful for large strings.

$text = <<<TEXT
Hello
World
TEXT;

Nowdoc

No interpolation.

$text = <<<'TEXT'
Hello $name
TEXT;

Accessing Characters

$name = "Aayan";

echo $name[0];

Output:

A

String Functions

PHP provides hundreds of functions.

strtoupper()

Converts to uppercase.

echo strtoupper(
    "zyro"
);

Output:

ZYRO

strtolower()

echo strtolower(
    "ZYRO"
);

Output:

zyro

ucfirst()

echo ucfirst(
    "aayan"
);

Output:

Aayan

ucwords()

echo ucwords(
    "zyro network"
);

Output:

Zyro Network

trim()

Removes spaces.

$name = "  Aayan ";

echo trim($name);

ltrim()

Removes left spaces.

rtrim()

Removes right spaces.

str_replace()

Replace text.

echo str_replace(
    "Hello",
    "Hi",
    "Hello World"
);

Output:

Hi World

str_ireplace()

Case-insensitive replacement.

strpos()

Find first occurrence.

echo strpos(
    "Hello World",
    "World"
);

Output:

6

stripos()

Case-insensitive search.

str_contains()

PHP 8+

if (
    str_contains(
        $message,
        "hello"
    )
) {

}

str_starts_with()

str_starts_with(
    "PocketMine",
    "Pocket"
);

str_ends_with()

str_ends_with(
    "plugin.yml",
    ".yml"
);

substr()

Extract portion of string.

echo substr(
    "PocketMine",
    0,
    6
);

Output:

Pocket

explode()

Convert string into array.

$data =
explode(
    ",",
    "A,B,C"
);

Output:

[
    "A",
    "B",
    "C"
]

implode()

Convert array into string.

echo implode(
    ", ",
    [
        "A",
        "B",
        "C"
    ]
);

Output:

A, B, C

nl2br()

Convert new lines to HTML.

wordwrap()

Wrap long strings.

str_repeat()

echo str_repeat(
    "=",
    20
);

Output:

====================

str_pad()

echo str_pad(
    "VIP",
    10
);

number_format()

echo number_format(
    1500000
);

Output:

1,500,000

HTML Functions

htmlspecialchars()

Extremely important for security.

echo htmlspecialchars(
    "<script>"
);

Output:

&lt;script&gt;

htmlentities()

Converts special characters.

String Comparison

==

"abc" == "abc"

===​

"abc" === "abc"

strcmp()​

strcmp(
    "abc",
    "abd"
);

Returns:

-1
0
1

String Interpolation

$name = "Aayan";

echo "Hello {$name}";

Recommended syntax:

{$variable}

Variable Parsing

echo "Player: {$player->getName()}";

Multibyte Strings

For UTF-8 languages use:

mb_strlen()
mb_substr()
mb_strtoupper()

Install extension:

sudo apt install php-mbstring

Regular Expressions

PHP supports regex.

preg_match()

preg_match(
    "/hello/",
    "hello world"
);

preg_replace()

preg_replace(
    "/[0-9]/",
    "",
    "abc123"
);

Output:

abc

preg_split()

Split using regex.

PocketMine Examples

Chat Formatting

$message =
"§6Zyro §8» §fHello";

Color Codes

str_replace(
    "&",
    "§",
    $message
);

Command Parsing

$args =
explode(
    " ",
    $command
);

Config Values

$prefix =
$config->get(
    "prefix"
);

JSON APIs

$json =
json_encode(
    [
        "name" => "Aayan"
    ]
);

Validation Examples

Username Length

if (
    strlen($name) < 3
) {

}

Email Check

if (
    str_contains(
        $email,
        "@"
    )
) {

}

Permission Check

if (
    str_starts_with(
        $permission,
        "zyro."
    )
) {

}

Common Mistakes

Using == for Search​

❌

if (
    strpos(
        $text,
        "hello"
    )
)

Fails if result is:

0

✅

if (
    strpos(
        $text,
        "hello"
    ) !== false
)

Forgetting UTF-8​

❌

strlen("नमस्ते")

✅

mb_strlen("नमस्ते")

Concatenating Too Much​

Avoid:

$a . $b . $c . $d . $e

Prefer:

sprintf()

Best Practices

✅ Use:

str_contains()

instead of:

strpos()

when possible.

✅ Escape HTML output.

✅ Use UTF-8.

✅ Prefer interpolation:

"Hello {$name}"

Exercises

Exercise 1​

Convert:

zyronetwork

to uppercase.

Exercise 2​

Split:

apple,banana,mango

using:

explode()

Exercise 3​

Join array using:

implode()

Exercise 4​

Replace:

&

with:

§

Mini Project

Create a chat formatter:

&6Admin:
Hello

Output:

§6Admin:
Hello

Challenge

Create:

formatMoney()
formatPlayerName()
formatRankPrefix()

Quiz

Which function returns string length?​

Answer

strlen()

Which function converts string to array?​

Answer

explode()

Which function joins arrays?​

Answer

implode()

Which function checks substring?​

Answer

str_contains()

Useful Links

PHP Strings:

https://www.php.net/manual/en/book.strings.php

String Functions:

https://www.php.net/manual/en/ref.strings.php

Regex:

https://www.php.net/manual/en/ref.pcre.php

Next Chapter

➡ PHP Arrays