Common PHP String Functions and Usage Examples

PHP provides a rich set of string functions that help developers manipulate text efficiently. This tutorial introduces the most commonly used PHP string functions, grouped by purpose, and demonstrates their usage with clear code examples.

Getting String Information

strlen()

: Get the length of a string substr(): Extract a portion of a string strstr(): Find a substring strchr(): Find the last occurrence of a character in a string

Processing Strings

str_replace()

: Replace characters within a string trim(): Remove whitespace from the beginning and end of a string str_pad(): Pad a string to a certain length str_split(): Split a string into an array

Converting Strings

strtolower()

: Convert a string to lowercase strtoupper(): Convert a string to uppercase ucfirst(): Capitalize the first character of a string lcfirst(): Lowercase the first character of a string

Example Code:

// Get string length
$str = "Hello, world!";
$length = strlen($str);
echo "The length of the string is $length characters.";

// Extract substring
$str = "Hello, world!";
$sub_str = substr($str, 0, 5);
echo $sub_str; // Hello

// Find substring
$str = "Hello, world!";
$pos = strpos($str, ",");
echo $pos; // 5

// Find last occurrence
$str = "Hello, world!";
$pos = strrpos($str, ",");
echo $pos; // 10

// Replace characters
$str = "Hello, world!";
$str = str_replace("world", "PHP", $str);
echo $str; // Hello, PHP!

// Trim whitespace
$str = "  Hello, world!  ";
$str = trim($str);
echo $str; // Hello, world!

// Pad string
$str = "Hello, world!";
$str = str_pad($str, 20, "-");
echo $str; // -----Hello, world!-----

// Split string into array
$str = "Hello, world!";
$arr = str_split($str, 5);
print_r($arr); // Array ( [0] => Hello [1] => world! )

// Convert to lowercase
$str = "Hello, world!";
$str = strtolower($str);
echo $str; // hello, world!

// Convert to uppercase
$str = "Hello, world!";
$str = strtoupper($str);
echo $str; // HELLO, WORLD!

// Capitalize first letter
$str = "hello, world!";
$str = ucfirst($str);
echo $str; // Hello, world!

// Lowercase first letter
$str = "HELLO, WORLD!";
$str = lcfirst($str);
echo $str; // hello, world!

Conclusion

PHP's string functions enable developers to handle text quickly and effectively; mastering them can improve development efficiency and code quality.