Formatting arrays and nested arrays with the print function in PHP

Question

I'm having problems formatting arrays and nested arrays with print function in PHP.

So far into learning PHP, I have been wrapping print commands with " " and putting basic html like  within the quotes with the single variables, and everything works fine. Today I have been creating arrays and nested arrays and have been getting some strange behaviour.

For instance:

// nested array
$array2 = array(6, "fox", "dog", array("x", "y", "z"));
// display nested array index 1
print "<p> $array2[3][1] </p>";

This prints Array[1] instead of y.

If I do this it prints ok:

print "<p>" . $array2[3][1] . "</p>";

The last array I am trying to get to print using a print readible with <pre> tags. So far I have tried this, but all I see in the browser is just array

print_r("<pre>" . $array2 . "</pre>");

I must be doing something wrong if the tags will not concat?

You have to convert an array to string somehow. Check out the PHP's implode function php.net/manual/en/function.implode.php — Weltschmerz
– Weltschmerz, Commented Oct 21, 2014 at 15:40

h2ooooooo · Accepted Answer · 2014-10-21 15:42:52Z

1

When you use

print_r("<pre>" . $array2 . "</pre>");

You're concatenating the strings <pre> and </pre> with an array, it automatically converts the array to "Array", and it equal to the following:

print_r("<pre>" . (string)$array2 . "</pre>");

What you actually want to do is use print_r on the array itself - not turn it into a string. You can take use of the second parameter in print_r to return the value rather than outputting it:

echo '<pre>' . print_r($array2, true) . '</pre>';

answered Oct 21, 2014 at 15:42

h2ooooooo

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4 Comments

user1574598 Over a year ago

Thanks - I noticed your using single quotes, does this matter in this case? The only time I have used single quotes is in the $_POST function so far. Also, are echo and print the same?

h2ooooooo Over a year ago

How are echo and print different in PHP?. Essentially, echo is faster, but reacts a little differently (you probably won't notice the difference, so just use echo. When using single quotes variables inside do not expand (variable expanding is why echo "$test"; works. Use whichever you prefer as the speed difference is so minimal that it does not matter.

user1574598 Over a year ago

I see, thanks. So when you say "expand", what would happen if you wrote echo '$test' would this still be expanded, but will execute faster?

h2ooooooo Over a year ago

@user1574598 No - single quotes don't expand. $test = 'abc'; echo "$test"; would output 123. $test = 'abc'; echo '$test'; would output $test. Don't bother about which is faster - it's micro optimization and is not needed. Bother about what you find easiest to read.

Pedro Amaral Couto · Accepted Answer · 2014-10-21 15:59:59Z

1

You should add curly brackets:

// nested array
$array2 = array(6, "fox", "dog", array("x", "y", "z"));
// display nested array index 1
print "<p> {$array2[3][1]} </p>";

From the manual:

If a dollar sign ($) is encountered, the parser will greedily take as many tokens as possible to form a valid variable name. Enclose the variable name in curly braces to explicitly specify the end of the name.

answered Oct 21, 2014 at 15:59

Pedro Amaral Couto

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