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PHP: Standard Library

PHP, like any other language, comes with a set of useful features. Altogether, they make up the so-called standard library. It usually contains thousands of functions you can't remember, and that you don't have to. It's assumed that any programmer knows where to look for their documentation and has a rough idea of what they want to achieve. And the rest is a matter of technique. Programming without the Internet is extremely difficult.

To newcomers, it often looks like this: "Go I know not whither and fetch I know not what". In other words, most people have no idea how to learn about these functions when they don't know anything at all. Oddly enough, there's no way to know everything you need to know once and for all. As you grow as a developer, you'll learn all the exciting features that can solve your problems more elegantly, thus expanding your toolbox.

Here are some tips to learn about new features:

  • Always keep track of what you're working with at the moment (the data type). You'll almost always find the function you need in the corresponding section of the documentation, e.g. you have to study string functions to work with strings.
  • Open the standard functions section of the topic you are studying every now and then and just run through them,, learning the signatures and ways to use them.
  • Read other people's code more often, especially code from the libraries you're using. It's all available on GitHub.

Another feature of PHP functions from the Standard Library is that they're available globally. In other words, you can call them anywhere in your program (this doesn't work with functions you've written yourself). Most standard library functions are centered around some functionality or some type of data. For example, there's a large block of functions for processing strings, working with numbers, and so on. We'll go over some of them as you continue to study.


The gettype() function allows you to determine the type of the argument being passed. The name of the type is returned as a string. For example, a call to gettype(10) will return the string "integer".

Print the type of the value of the variable $motto.

The exercise doesn't pass checking. What to do? 😶

If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:

  • Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨

Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.

My code is different from the teacher's one 🤔

It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.

In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.

I've read the lessons but nothing is clear 🙄

It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.

By the way, you can participate in courses improvement. There is a link below to the lessons course code which you can edit right in your browser.



  • Standard Library a set of useful features included with the programming language.

If you got stuck and don't know what to do, you can ask a question in our community