Comparing Strings

aksival

Theoretically, two compare two strings we would say:

if ($string1==$string2) {

}

So, if we know that $string1 is indeed a string, why doesn't this work:

if ($string1=="text") {

}

In addition, why doesn't this work:

$string2="text";

if ($string1==$string2) {

}

Is this something to do with variable definitions?

Thanks for any help in advance!

tomhath

What do you mean by "doesn't work"? Doesn't compile? Or doesn't give the answer you expect? Try echoing what's in $string to be sure you have what you think.

<?php 
$string1 = "test";

if ($string1 == "test") {
  echo "Works for me";
}

echo "<BR>";

$string2 = "test";
if ($string1 == $string2) {
  echo "Also works for me";
}
?>

aksival

Sorry, my example was incorrect. What I meant was comparing variables to null strings:

if ($string1=='") {

}

or a string variable to a non-variable string:

if ($string1=="HELLO") {

}

This compiles but it doesn't work. The conditional is ignored every time, even if the variable matches the compared string.

Sorry about the mistake.

diego25

I'm not sure what you're talking about...I've tried this:

<?php
$string = "";
if ($string == "") {
	print "PHP is cool\n";
} else {
	print "PHP is wrong!\n";
}

$string = "HELLO";
if ($string == "HELLO") {
	print "PHP is cool, again!";
} else {
	print "PHP is very wrong!";
}
?>

and it works perfectly fine...

Diego

aksival

Yes, the same code works for me, too. Would it make a difference if the data being checked comes from a form?

$data=$_POST["data"];

if ($string1 == $data) {

echo "works right";

} else {

echo "not working";

}

With this I keep getting the "not working" message, but if I echo the $data, it is what it's supposed to be. Weird...

Floodboy

Try using single quotes

$data=$_POST['data'];

if ($string1 == $data) { 

echo "works right"; 

} else { 

echo "not working"; 

}

diego25

Maybe it has some special characters in it? like newlines and such? Try

if ($string1 == trim($data)) {

Diego