PHP Cookbook

Chapter 3. Functions

Every computer program in every language is built by tying various components of business logic together. Often, these components need to be somewhat reusable, encapsulating common functionality that needs to be referenced in multiple places throughout an application. The easiest way to make these components modular and reusable is to encapsulate their business logic into functions, specific constructs within the application that can be referenced elsewhere throughout an application.

Example 3-1 illustrates how a simple program might be written to capitalize the first character in a string. Coding without using functions is considered imperative programming, as you define exactly what the program needs to accomplish one command (or line of code) at a time.

Example 3-1. Imperative (function-free) string capitalization

$str = "this is an example";

if (ord($str[0]) >= 97 && ord($str[0]) <= 122) {
    $str[0] = chr(ord($str[0]) - 32);
}

echo $str . PHP_EOL; // This is an example

$str = "and this is another";

if (ord($str[0]) >= 97 && ord($str[0]) <= 122) {
    $str[0] = chr(ord($str[0]) - 32);
}

echo $str . PHP_EOL; // And this is another

$str = "3 examples in total";

if (ord($str[0]) >= 97 && ord($str[0]) <= 122) {
    $str[0] = chr(ord($str[0]) - 32);
}

echo $str . PHP_EOL; // 3 examples in total

Note

The functions ord() and chr() are references to native functions defined by PHP itself. The ord() function returns the binary value of a character as an integer. Similarly, ...