Top 25 PHP Functions Every Developer Should Know

PHP provides hundreds of built-in functions that make web development easier. Whether you're creating forms, handling files, working with databases, or manipulating strings, knowing the right functions can save time and improve your code.

In this guide, you'll learn 25 essential PHP functions with examples.

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1. echo()

Outputs text to the browser.

<?php
echo "Hello, World!";
?>

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2. print()

Prints a string.

<?php
print "Welcome to PHP!";
?>

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3. strlen()

Returns the length of a string.

<?php
echo strlen("PHP Tutorial");
?>

Output:

12

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4. str_word_count()

Counts the number of words.

<?php
echo str_word_count("Learn PHP Programming");
?>

Output:

3

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5. strtoupper()

Converts text to uppercase.

<?php
echo strtoupper("php");
?>

Output:

PHP

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6. strtolower()

Converts text to lowercase.

<?php
echo strtolower("HELLO");
?>

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7. ucfirst()

Capitalizes the first letter.

<?php
echo ucfirst("php tutorial");
?>

Output:

Php tutorial

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8. ucwords()

Capitalizes every word.

<?php
echo ucwords("learn php programming");
?>

Output:

Learn Php Programming

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9. trim()

Removes spaces from both ends.

<?php
$name = "  Sunil  ";
echo trim($name);
?>

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10. explode()

Converts a string into an array.

<?php
$text = "PHP,HTML,CSS";
print_r(explode(",", $text));
?>

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11. implode()

Joins array elements into a string.

<?php
$arr = ["PHP","HTML","CSS"];
echo implode(", ", $arr);
?>

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12. date()

Displays the current date.

<?php
echo date("Y-m-d");
?>

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13. time()

Returns the current Unix timestamp.

<?php
echo time();
?>

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14. rand()

Generates a random number.

<?php
echo rand(1,100);
?>

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15. abs()

Returns the absolute value.

<?php
echo abs(-25);
?>

Output:

25

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16. round()

Rounds a decimal number.

<?php
echo round(9.67);
?>

Output:

10

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17. max()

Returns the largest value.

<?php
echo max(10,20,50,30);
?>

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18. min()

Returns the smallest value.

<?php
echo min(10,20,50,30);
?>

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19. isset()

Checks whether a variable exists.

<?php
$name = "Sunil";

if(isset($name)){
    echo "Variable Exists";
}
?>

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20. empty()

Checks whether a variable is empty.

<?php
$name = "";

if(empty($name)){
    echo "Empty Variable";
}
?>

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21. array_push()

Adds an element to an array.

<?php
$colors = ["Red","Blue"];
array_push($colors,"Green");

print_r($colors);
?>

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22. count()

Counts array elements.

<?php
$numbers = [10,20,30,40];

echo count($numbers);
?>

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23. in_array()

Checks if a value exists in an array.

<?php
$colors = ["Red","Green","Blue"];

if(in_array("Green",$colors)){
    echo "Found";
}
?>

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24. file_exists()

Checks if a file exists.

<?php
if(file_exists("test.txt")){
    echo "File Found";
}
?>

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25. password_hash()

Hashes passwords securely.

<?php
$password = "admin123";

$hash = password_hash($password, PASSWORD_DEFAULT);

echo $hash;
?>

Always use password_hash() for storing passwords instead of plain text.

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Best Practices

• Use built-in PHP functions instead of writing custom code whenever possible.

• Validate user input before processing.

• Use password_hash() and password_verify() for authentication.

• Read the PHP documentation to understand function parameters and return values.

• Write clean, reusable, and well-commented code.