We are already familiar with the mathematical operation of addition. This program:
<?php print_r(5 + 3);
will print '8' to the screen, which is the result of operation of binary operator '+' with operands '5' and '3'.
Strings can be manipulated too. You can "add" two strings. This program:
<?php print_r('Dragon' . 'stone');
Dragonstone to the screen - the result of operation of binary operator '+' with operands 'Dragon' and 'stone'.
Such operation is called concatenation. Roughly speaking, it's 'glueing' strings together. Such glueing always happens in the same order as the operands follow each other, in other words, the left operands becomes the left part of the string, and the right operand - the right part.
Here are some more examples:
<?php print_r('Kings' . 'wood'); // => Kingswood print_r('Kings' . 'road'); // => Kingsroad print_r("King's" . 'Landing'); // => King'sLanding
As you see from examples above, strings can be concatenated even if they are specified with different quotation marks.
In the last example we got the name of the city printed incorrectly: King's Landing must have a space between words! The original strings, however, didn't have spaces, and the spaces to the right and left of
. are not interpreted as part of strings.
We can fix this in several ways:
<?php //Adding a space at the end of the left part print_r("King's " . 'Landing'); // => King's Landing //Adding a space at the end of the right part print_r("King's" . ' Landing'); // => King's Landing
The more spaces we add, the wider interval we get:
<?php print_r("King's " . ' Landing'); // => King's Landing print_r("King's " . ' Landing'); // => King's Landing
Print to the screen
Winter came for the House of Frey.
using word concatenation.
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.
Concatenation - operation of joining two strings. For example, print_r("King's " . ' Landing');`