The 3 different equals

Question

Can someone explain to me the difference between =, ==, and ===? I think using one equal sign is to declare a variable while two equal signs is for a comparison condition and lastly three equal signs is for comparing values of declared variables.

Answer 1

You are right that = is the assignment operator. The other two are comparison operators that you can read more about here.

Answer 2

You have = the assignment operator, == the 'equal' comparison operator and === the 'identical' comparison operator.

$a = $b     Assign      Sets $a to be equal to $b.
$a == $b    Equal       TRUE if $a is equal to $b.
$a === $b   Identical   TRUE if $a is equal to $b, and they are of the same type. (introduced in PHP 4) 

For more info on the need for == and ===, and situations to use each, look at the docs.

Answer 3

Take a look at the manual: http://www.php.net/manual/en/language.operators.comparison.php

Answer 4

= assignment operator

== checks if two variables have the same value

=== checks if two variables have the same value AND if their types are the same

Answer 5

• = is the assignment operator
• == is the comparison operator (checks if two variables have equal values)
• === is the identical comparison operator (checks if two variables have equal values and are of the same type).

Answer 6

Everyone else have clarified .. I just want to add an example to clarify it more ..

<?php
$mystring = 'abc';
$findme   = 'a';
$pos = strpos($mystring, $findme);

// Note our use of ===.  Simply == would not work as expected
// because the position of 'a' was the 0th (first) character.
if ($pos === false) {
    echo "The string '$findme' was not found in the string '$mystring'";
} else {
    echo "The string '$findme' was found in the string '$mystring'";
    echo " and exists at position $pos";
}
?> 

Answer 7

Maybe you can better comprehend the difference between == and === with an example that involves automatic casting:

echo '"5 is not a number" == 5'."\n";
if("5 is not a number" == 5) {
  echo "maybe there is something wrong here\n";
} else {
  echo " The integer and the string are different\n";
}
echo '"5 is not a number" === 5'."\n";
if("5 is not a number" === 5) {
  echo "maybe there is something wrong here\n";
} else {
  echo " The integer and the string are different\n";
}