How many php functions

A user-defined function declaration starts with the word function :. Note: A function name must start with a letter or an underscore. Function names are NOT case-sensitive. In the example below, we create a function named "writeMsg ". The function outputs "Hello world! To call the function, just write its name followed by brackets :. Arguments are specified after the function name, inside the parentheses.

You can add as many arguments as you want, just separate them with a comma. When the familyName function is called, we also pass along a name e. Jani , and the name is used inside the function, which outputs several different first names, but an equal last name:. PHP automatically associates a data type to the variable, depending on its value. Since the data types are not set in a strict sense, you can do things like adding a string to an integer without causing an error.

In PHP 7, type declarations were added. Consider the above example one last time. This, in effect, scopes the variable both within and outside of the function. A slightly more advanced attribute of functions is recursion. Recursion is when a function is written so it can call itself. A recursive function must contain an end condition, which will cause the function to terminate. Typically, when writing a recursive function there will be a 'base case' that is tested for within the function, and the function will continue to call itself until the 'base case' is satisfied.

Here's what an example of what the code would look like:. While the definition of an anonymous function is the same as a user-defined function — namely that it accepts arguments, works with variables, and contains code logic — the function has no name and ends with a semicolon. This is because unlike regular functions, which are code constructions, an anonymous function is an expression. Consider an earlier example, which I code here as an anonymous function:. This anonymous function code can never be called.

The semicolon at the end of the function definition ensures that the function is treated as an expression. Since it is treated as an expression, it can be assigned to a variable, allowing it to be called by referencing the variable.

It can also be passed to another function, which makes the anonymous function a callback. Another point to make about anonymous functions is that they can be returned from another function. This is referred to as a closure. The latest version of PHP, 7. This is helpful in writing tighter code. Also notice that the return keyword is not necessary for single expressions.

Anonymous functions are most useful as the value of callback parameters, but they have other use cases. They are throw-away functions when you need a function that you want to only use once. At the beginning of this blog, I mentioned that in the procedural world of PHP , functions are similar to what object-oriented developers call methods.

Look at the highlighted portion of the above code. Notice that even though we are in a class definition, the keyword function defines what object-oriented developers call a method. So really, method can be another name for a function. Following example creates a function called writeMessage and then calls it just after creating it.

PHP gives you option to pass your parameters inside a function. You can pass as many as parameters your like. These parameters work like variables inside your function. Following example takes two integer parameters and add them together and then print them. It is possible to pass arguments to functions by reference. This means that a reference to the variable is manipulated by the function rather than a copy of the variable's value.

Any changes made to an argument in these cases will change the value of the original variable. You can pass an argument by reference by adding an ampersand to the variable name in either the function call or the function definition.