Introduction to PHP Functions
Great job! Let’s review what we covered in this lesson:
- We can package a set of instructions within a named function to reuse whenever we’d like.
- When we invoke a function, the computer will execute the function body, specified by the code block following the parameters list.
- Functions can return a value by using the
returnkeyword otherwise they return
NULLwhich means no value.
- We can store the return value of a function in a variable or use it any other way we’d use a value.
- We can define functions with parameters which are variables we can refer to throughout our function’s body.
- When invoking functions, the values that we give them are called arguments.
- Functions can have multiple parameters.
- The order in which the arguments are passed in decides which parameters they correspond to.
- You can make an argument optional by providing its corresponding parameter with a default value.
- If you prepend a parameter with the reference sign (
&) that argument will be passed by reference.
- Variables within functions have local scope and can not be accessed from outside the function.
- Use the
globalkeyword to use variables from the global scope within a function.
Take a look at this diagram of the syntax for defining and calling functions.