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PHP: Errors when handling variables

The main rule is that a variable must be declared before it can be used. If you do it later, the program simply won't work.


$greeting = 'Father!';

Running the program above ends with an error PHP Notice: Undefined variable: greeting. Undefined variable It means that the code uses a name (the proper term is 'identifier') that hasn't been defined. And in the error itself, the variable identifier is explicitly specified: greeting. In addition to defining things in the wrong order, there are other, more trivial errors that can occur in PHP, for example, typos, both when using a variable and declaring one

The number of these errors can be reduced by using a properly configured editor. An editor like this highlights names that are used without announcement and warns of possible problems.


Find an undeclared variable in the program and declare it by assigning the value 'Dragon' to it.

After running the program, the result on the screen should look like this:

Targaryen and Dragon
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.

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