Explain Library Functions in PHP with Example

Library functions are pre-defined, built-in functions provided by PHP that help developers perform common tasks easily. Instead of writing code from scratch, you can use these ready-made functions to handle strings, arrays, files, dates, math operations, and more. They make programming faster, cleaner, and more efficient.

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What Are Library Functions?

Library functions (also called built-in functions) are functions that come bundled with PHP.
They are always available and can be used directly without defining them.

Examples include:

• strlen() – count string length
• array_push() – add an element to an array
• date() – work with date and time
• sqrt() – mathematical square root

PHP has 1000+ built-in functions, covering almost every programming need.

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Advantages of Library Functions

• Saves development time
• Highly optimized for performance
• Well-tested and reliable
• Easy to use
• Comes with official documentation

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Categories of PHP Library Functions

✔ 1. String Functions

Used for manipulating and analyzing text.

Examples:

echo strlen("Savanka");   // Output: 7
echo strtolower("HELLO"); // Output: hello

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✔ 2. Array Functions

Help manage array elements.

Example:

$fruits = ["apple", "banana"];
array_push($fruits, "mango");
print_r($fruits);

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✔ 3. Mathematical Functions

Perform mathematical operations.

Example:

echo sqrt(49); // 7
echo rand(1, 100);

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✔ 4. Date & Time Functions

Used for formatting and managing dates.

Example:

echo date("Y-m-d");

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✔ 5. File System Functions

Work with files and folders.

Example:

$file = fopen("demo.txt", "w");
fwrite($file, "Hello World");
fclose($file);

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✔ 6. Error Handling Functions

Used to manage runtime errors.

Example:

error_log("Something went wrong!");

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✔ 7. Misc Functions

Thousands of other helpful functions like:

• isset()
• empty()
• die()
• var_dump()

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Why Use Library Functions?

• Reduce code complexity
• Increase productivity
• Avoid bugs
• Improve performance
• Make applications more stable

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Citations

🔗 View other articles about PHP:
http://savanka.com/category/learn/php/

🔗 External PHP Documentation:
https://www.php.net/manual/en/