This lesson will give a basic introduction to functions and its types, like inbuilt and user-defined functions, as well as their PHP syntax.

What is a Function? #

A function is a block of code that is written in order to perform a specific task.

Let’s discuss a real-life example to understand the concept better. Suppose that a headmaster wants a teacher to calculate the average marks of the students in a class for a particular subject. The teacher will note down all the marks of the students for that subject, perform the required calculations to calculate the average mark and then report the result to the headmaster.

Functions work in a similar way. They take the required information to perform a task as input parameter(s), perform the required operations on these parameters, and then they return the final answer.

Types of Functions #

In PHP there are two major types of functions:

  • Built-in functions
  • User-defined functions

Built-in Functions #

PHP already provides quite a few built-in functions that a user can use. These functions are pre-defined and just need to be called. Here is a list of built-in functions in PHP.

User-defined Functions #

Apart from built-in functions, PHP also allows us to make our own customized functions. These functions can be written such that they would perform the required task wherever necessary once they’re called.

Implementation #

Now let’s discuss the method to write a user-defined function below.

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