Help printing emptiness in PHP

[Lunar Evolution]

So I really need to figure out what I'm doing wrong and why exactly my if statement is never true, but I can't figure out without getting this to actually print anything:

echo strpos($output, "[servername] => $servername");

But I cannot seem to figure out why it always just prints nothing. I'm very new to PHP, I usually work with Python or Java. Am I just missing something? Is there any way to get it to print "false" or "null" when it can't find the position?

[Kryptyx]

Can you explain more what you are trying to do. PHP docs are very good: http://php.net/manual/en/function.strpos.php

[Lunar Evolution]

1 minute ago, Kryptyx said:

Can you explain more what you are trying to do.

Ultimately the code will look something like this:

    if (strpos($output, "[servername] => $servername") != false) {

        echo "There is a $serverstatus alert on the $servername server where one of your products is hosted.";
    }

But the strpos function keeps outputting nothing. It doesn't evaluate to false or true or "" or null. So I need to figure out what its outputting in order to figure out how to fix the problem.

[Kryptyx]

Since the $servername variable is in double quotes it will get resolved.

[Lunar Evolution]

43 minutes ago, Kryptyx said:

Since the $servername variable is in double quotes it will get resolved.

What do you mean? The variable has to be in double quotes to register as a variable and not just more text, but it won't print either way

[Kryptyx]

Right, just making sure you knew it was getting evaluated.

So to be clear, you can't echo a boolean. You can use var_dump if you want to test the value and print that.

 

Example:

var_dump(strpos($output, "[servername] => $servername"));

 

[Hazy125]

The echo statement does not return a truth value. Just use print instead. Print works just as well in PHP

[Lunar Evolution]

42 minutes ago, Kryptyx said:

Right, just making sure you knew it was getting evaluated.

So to be clear, you can't echo a boolean. You can use var_dump if you want to test the value and print that.

 

Example:

var_dump(strpos($output, "[servername] => $servername"));

 

Thanks, that's exactly what I was looking for. So I figured out it's returning false every time, but it's even returning false where it's looking for a string that I know is contained in the $output variable.

For example:

$servername = "s9";
$thestring = "[servername] => $servername";

var_dump(strpos($output, $thestring));
var_dump(strpos($output, "[servername] => s9"));

The first var_dump returns bool(false), but the second returns the position in the $output variable. From what I can tell, these are exactly the same when just echoed, so is there any reason that it isn't working once I use it with the strpos function?

[Kryptyx]

The following code works, results in `int 17`.
 

$servername = "s9";
$thestring = "[servername] => $servername";
$output = "[hello] => world
[servername] => s9
[linus] => techtips";

var_dump(strpos($output, "[servername] => $servername"));

[Lunar Evolution]

4 hours ago, Kryptyx said:

The following code works, results in `int 17`.
 

$servername = "s9";
$thestring = "[servername] => $servername";
$output = "[hello] => world
[servername] => s9
[linus] => techtips";

var_dump(strpos($output, "[servername] => $servername"));

Yeah you're right. So I tested this exact code except with my setup. The only difference is that I'm actually reading the $servername variable out of a txt file. It's on a line by itself and is the only thing printed when I print the specific line, but it doesn't work with the strpos function. I didn't think it mattered that it was being read from a file but that seems to be where the issue originates. I took your code and modified it to this:

$file = "status.txt";
$lines = file($file, FILE_IGNORE_NEW_LINES);

$servername = $lines[1];
$thestring = "[servername] => $servername";
$output = "[hello] => world
[servername] => s9
[linus] => techtips";

echo $servername;
var_dump(strpos($output, "[servername] => $servername"));

It now results int 's9bool(false)'

 

So even though it is still just s9, the strpos now returns false. Maybe you know the cause, but I am somewhat lost.

[mariushm]

Also keep in mind that some functions can return FALSE or a value that is evaluated as FALSE by the !=  or == .  If you really want to check against only FALSE (boolean), you have to use !== or ===

See http://php.net/manual/en/language.operators.comparison.php and hopefully it makes sense to you.

[prolemur]

Lol if it's not false, so if it's true

[Lunar Evolution]

9 hours ago, prolemur said:

Lol if it's not false, so if it's true

Well usually the strpos() function will return false if not found or an integer if found, if I understand correctly