A Php program to print the string using function. By using this program we can print the elements and string using functions. A function is a collection of statements that can be used over and over again in a program. When a page loads, a function will not run automatically. A call to a function will cause it to be performed. A function is a piece of code that takes another input in the form of a parameter, processes it, and then returns a value. Although these are built-in functions, PHP also allows you to construct your own.