Print false in php

Question

I am trying to print the following statement:

print false . "\n" . true . "\n";
echo false . (bool)false . "\n" . true . "\n";
print "0" . "\n" . true . "\n";

The result that I am getting is just "1 1 0 1". The expected result is:

0
1
0
1
0
1

I am using PHP 5.4.3 MSVC9 x64 Can someone please explain why and how I can make it print the correct way?

score 10 · Answer 1 · edited May 23 '17 at 11:56

10

Your problem comes from your misconception of the + operator on strings in PHP. The string concatenation operator is . as PHP is loosely typed, it doesn't know if you want to concat or add the strings.

I'll break it down for you:

print false + "\n" + true + "\n";
echo false+(bool)false + "\n" + true + "\n";
print "0" + "\n" + true + "\n";

First off you might want to pick to stay with echo or print. Now, onward:

print false + "\n" + true + "\n";

PHP strings, when added (not contacted), evaluate to 0. So this statement evaluates to:

print 0 + 0 + 1 + 0;

which is 1. The other ones follow suit. If you want your code to work, you should use the concatenation operator (.). If you want to write True or False like how .NET does, you could write a simple function:

function writeBool($var)
{
    echo ($var) ? "True" : "False";
}

As per PHP's loose typing (which sucks if you ask me), anything that will evaluate to true, will write "True". I would still discourage from using a function to do this as function calls in PHP are expensive.

edited May 23 '17 at 11:56

Community

1
1

answered Jul 16 '12 at 21:19

Cole Tobin

9,206
15
49
74

3

explanation to follow shortly... but already has +5 :P Now **THAT** is hype! – Lix Jul 16 '12 at 21:21
2

A very good explanation just doesn't solve my problem – Randall Flagg Jul 16 '12 at 21:28
@RandallFlagg added a little function. PHP is loosely typed and `false` is just defined as 0: `define("false", 0);`. Same for true: `define("true", 1);` – Cole Tobin Jul 16 '12 at 21:29
@ColeJohnson That's... really not how it is. – JJJ Jul 16 '12 at 21:30
@Juhana its just explination. It's not how they really are. :/ (unless you're C or C++) – Cole Tobin Jul 16 '12 at 21:30
2

"The moon is made of cheese. It's not really, it's just an explanation." – JJJ Jul 16 '12 at 21:31
@ColeJohnson Why "echo true" gives 1 but "echo false" doesn't print? – Randall Flagg Jul 16 '12 at 21:33
@RandallFlagg http://ideone.com/AiROT I have no idea. – Cole Tobin Jul 16 '12 at 21:34
@ColeJohnson Do you know why it doesn't break lines? – Randall Flagg Jul 16 '12 at 21:39
1

@RandallFlagg Probably because you're looking at it in a web browser. Either choose "View source" in the browser or change the newlines to `
`s. – JJJ Jul 16 '12 at 21:43
1

I was right here in this thread before I clicked on Cole Johnson's profile to find out that he is 15. Kudos to Cole Johnson. I started thinking about typesystems when I turned 21. – hrishikeshp19 Sep 24 '12 at 18:15

score 2 · Accepted Answer · answered Jul 16 '12 at 21:33

2

This should do the trick. Use an array.

$boolarray = Array(false => 'false', true => 'true');
echo $boolarray[false],"  ", $boolarray[true];

Output : false true

answered Jul 16 '12 at 21:33

Lion

18,729
22
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@Lion Do you know how to print them on two lines? – Randall Flagg Jul 16 '12 at 21:42
`echo $boolarray[false],"
", $boolarray[true];`? Simply using a line-feed `
`. – Lion Jul 16 '12 at 21:44
Not the answer I wanted but it will have to do. I would prefer a solution from within the language so I won't need to decalre / import this array every time. – Randall Flagg Jul 16 '12 at 22:25
See [this](http://stackoverflow.com/questions/4948663/php-get-bool-to-echo-false-when-false) question. What I mentioned in my answeris also there. I have just found it. Also, tried `echo (int)$bool_val;` as mentioned there in of the answers but unfortunately it also didn't work. – Lion Jul 16 '12 at 22:29
@Lion I tried that. I also tried Intval. Thanks anyway. – Randall Flagg Jul 16 '12 at 22:40
Tried much more. Apart from all of them, `echo (string)$var` should have done the job but it also didn't work as your requirement. – Lion Jul 17 '12 at 21:17
In brief, you need to check conditionally like `if(true) echo "true"; else echo "false";` or the same thing using the ternary/conditional operator. If you are able to find a concise solution, don't forget to share here. – Lion Jul 18 '12 at 15:39
@Lion `
` is not a line feed, but a line break. – Cole Tobin Jul 20 '12 at 03:19
@Cole Johnson:) Good call. I was just sleepy and forgot that "*`
` stands for **break***". – Lion Jul 20 '12 at 18:54

Print false in php

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