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PHP: Default Arguments

Let's look at the round() function. It rounds up the number passed to it:


$result = round(10.25, 0); // 10

We passed two arguments to it: the number and the rounding accuracy. 0 means that the rounding will be to an integer value.

We usually need to round to a whole number (and not to 1 decimal point, for example), so the creators of the round function made the second argument optional and set the default value within the function to 0. So you can leave out the second argument and the result will be the same:


$result = round(10.25); // 10

And if you need to round it to a number of decimal places, then you can pass the required argument as well:


$result = round(10.25, 1); // 10.3

If a function in PHP takes optional arguments, they'll alway come after the required ones. Their number varies depending on the function itself, but they always go one after another and at the end of the list of arguments.


Round up the number written in the $number variable to two decimal places and display the result on the screen.

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

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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.

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I've read the lessons but nothing is clear 🙄

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  • The default argument is an optional function argument.

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