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    <h1>Difference between <code>==</code> and <code>===</code></h1> <p>The difference between the loosely <code>==</code> equal operator and the strict <code>===</code> identical operator is exactly explained in the <a href="http://php.net/manual/en/language.operators.comparison.php#language.operators.comparison" rel="noreferrer">manual</a>:</p> <blockquote> <p>Comparison Operators</p> <pre> ┌──────────┬───────────┬───────────────────────────────────────────────────────────┐ │ Example │ Name │ Result │ ├──────────┼───────────┼───────────────────────────────────────────────────────────┤ │$a == $b │ Equal │ TRUE if $a is equal to $b after type juggling. │ │$a === $b │ Identical │ TRUE if $a is equal to $b, and they are of the same type. │ └──────────┴───────────┴───────────────────────────────────────────────────────────┘ </pre> </blockquote> <hr /> <h1>Loosely <code>==</code> equal comparison</h1> <p>If you are using the <code>==</code> operator, or any other comparison operator which uses loosely comparison such as <code>!=</code>, <code>&lt;&gt;</code> or <code>==</code>, you always have to look at the <strong>context</strong> to see what, where and why something gets converted to understand what is going on.</p> <h3>Converting rules</h3> <ul> <li><a href="http://php.net/manual/en/language.types.boolean.php#language.types.boolean.casting" rel="noreferrer">Converting to boolean</a></li> <li><a href="http://php.net/manual/en/language.types.integer.php#language.types.integer.casting" rel="noreferrer">Converting to integer</a></li> <li><a href="http://php.net/manual/en/language.types.float.php#language.types.float.casting" rel="noreferrer">Converting to float</a></li> <li><a href="http://php.net/manual/en/language.types.string.php#language.types.string.casting" rel="noreferrer">Converting to string</a></li> <li><a href="http://php.net/manual/en/language.types.array.php#language.types.array.casting" rel="noreferrer">Converting to array</a></li> <li><a href="http://php.net/manual/en/language.types.object.php#language.types.object.casting" rel="noreferrer">Converting to object</a></li> <li><a href="http://php.net/manual/en/language.types.resource.php#language.types.resource.casting" rel="noreferrer">Converting to resource</a></li> <li><a href="http://php.net/manual/en/language.types.null.php#language.types.null.casting" rel="noreferrer">Converting to NULL</a></li> </ul> <h3>Type comparison table</h3> <p>As reference and example you can see the comparison table in the <a href="http://php.net/manual/en/types.comparisons.php#types.comparisions-loose" rel="noreferrer">manual</a>:</p> <blockquote> <p>Loose comparisons with <code>==</code></p> <pre>┌─────────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬─────────┬───────┬───────┐ │ │ TRUE │ FALSE │ 1 │ 0 │ -1 │ "1" │ "0" │ "-1" │ NULL │ array() │ "php" │ "" │ ├─────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼─────────┼───────┼───────┤ │ TRUE │ TRUE │ FALSE │ TRUE │ FALSE │ TRUE │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ │ FALSE │ FALSE │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ TRUE │ TRUE │ FALSE │ TRUE │ │ 1 │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ 0 │ FALSE │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ TRUE │ FALSE │ TRUE │ TRUE │ │ -1 │ TRUE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ │ "1" │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ "0" │ FALSE │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ "-1" │ TRUE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ │ NULL │ FALSE │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ TRUE │ FALSE │ TRUE │ │ array() │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ TRUE │ FALSE │ FALSE │ │ "php" │ TRUE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ │ "" │ FALSE │ TRUE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ TRUE │ └─────────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴─────────┴───────┴───────┘ </pre> </blockquote> <h1>Strict <code>===</code> identical comparison</h1> <p>If you are using the <code>===</code> operator, or any other comparison operator which uses strict comparison such as <code>!==</code> or <code>===</code>, then you can always be sure that the types won't <em>magically</em> change, because there will be no converting going on. So with strict comparison the type and value have to be the same, not only the value.</p> <h3>Type comparison table</h3> <p>As reference and example you can see the comparison table in the <a href="http://php.net/manual/en/types.comparisons.php#type.comparisons-strict" rel="noreferrer">manual</a>:</p> <blockquote> <p>Strict comparisons with <code>===</code></p> <pre>┌─────────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬─────────┬───────┬───────┐ │ │ TRUE │ FALSE │ 1 │ 0 │ -1 │ "1" │ "0" │ "-1" │ NULL │ array() │ "php" │ "" │ ├─────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼─────────┼───────┼───────┤ │ TRUE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ 1 │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ 0 │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ -1 │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ "1" │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ "0" │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ │ "-1" │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ FALSE │ │ NULL │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ FALSE │ │ array() │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ FALSE │ │ "php" │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ FALSE │ │ "" │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ FALSE │ TRUE │ └─────────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴─────────┴───────┴───────┘ </pre> </blockquote>
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    1. POHow do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?
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    1. COThis works much the same in Javascript, btw.
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    2. COthanks - i've added that to the tags now.
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    3. COdoes anyone else find it strange that "000" == "0000" ?
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