<p>The difference between == and === in PHP is that == compares values only, performing type coercion if necessary, while === checks both value and type, returning false if types differ. 1. == may lead to unexpected results due to type conversion, as seen in "5" == 5 returning true. 2. === ensures strict comparison, so "5" === 5 returns false because one is a string and the other is an integer. 3. != and !== behave similarly as opposites of == and ===, with !== being more predictable by checking both type and value. 4. Comparisons like >, =, </p> <p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175086996213258.jpg" class="lazy" alt="How do I use comparison operators in PHP (==, ===, !=, !==, >, <, >=, <=)?"></p> <p>When working with PHP, understanding how to use comparison operators correctly is key to writing logic that behaves as expected. These operators let you compare values in conditions, loops, and other control structures. Let’s go over the most commonly used ones — <code>==</code>, <code>===</code>, <code>!=</code>, <code>!==</code>, <code>></code>, <code>, <code>>=</code>, <code> — and see how they work in practice.</code></code></p> <hr> <h3 id="What-s-the-difference-between-and">What's the difference between == and ===?</h3> <p>This is one of the most important distinctions in PHP comparisons.</p> <ul> <li> <code>==</code> checks <strong>value only</strong>, not type. So <code>"5" == 5</code> returns true because both are considered equal when converted to the same type.</li> <li> <code>===</code> checks <strong>both value and type</strong>. That means <code>"5" === 5</code> returns false because one is a string and the other is an integer.</li> </ul> <p>It's generally safer to use <code>===</code> unless you're intentionally relying on type coercion. Otherwise, you might run into unexpected behavior due to PHP's loose typing.</p> <p>For example:</p><pre class='brush:php;toolbar:false;'>if (0 == "abc") { echo "This will print!"; }</pre><p>Here, <code>"abc"</code> is treated as 0 when compared loosely to an integer, which can be confusing if you're not expecting it.</p><hr /><h3 id="How-do-and-behave">How do != and !== behave?</h3><p>These are the opposites of <code>==</code> and <code>===</code>.</p><ul><li><code>!=</code> compares <strong>only value</strong>, returning true if values differ after type conversion.</li><li><code>!==</code> compares <strong>value and type</strong>, so it returns true if either differs.</li></ul><p>So just like before, using <code>!==</code> is more predictable:</p><pre class='brush:php;toolbar:false;'>null != 0; // true null !== 0; // also true, but for stricter reasons</pre><p>A common case where this matters is checking function return values. Some functions in PHP return <code>false</code> on failure or <code>0</code> as a valid result. Using <code>!=</code> could mix those up.</p><hr /><h3 id="Comparing-numbers">Comparing numbers: >, <, >=, <=</h3><p>These operators are straightforward when comparing numeric types:</p><ul><li><code>></code> means greater than</li><li><code><</code> means less than</li><li><code>>=</code> means greater than or equal to</li><li><code><=</code> means less than or equal to</li></ul><p>But again, PHP does type juggling by default. For example:</p><pre class='brush:php;toolbar:false;'>"10" > 2; // true, because "10" is converted to integer</pre><p>Even strings get compared character by character based on ASCII values if both sides aren't numeric:</p><pre class='brush:php;toolbar:false;'>"a" < "b"; // true "apple" > "banana"; // false, since 'a' comes before 'b'</pre><p>If you want strict numeric comparisons, make sure both operands are actually numbers before using these.</p><hr /><h3 id="When-should-I-cast-types-manually">When should I cast types manually?</h3><p>Sometimes, especially when dealing with user input or database results, values come in as strings even though they represent numbers.</p><p>In cases like that, casting can help avoid surprises:</p><pre class='brush:php;toolbar:false;'>$number = (int)$_GET['input']; if ($number > 100) { /* ... */ }</pre><p>Or, if you're comparing two variables and need to ensure type consistency:</p><pre class='brush:php;toolbar:false;'>if ((string)$a === (string)$b) { /* compare as strings */ }</pre><p>This gives you more control and avoids hidden bugs from automatic type conversion.</p> <hr> <p>That’s basically how comparison operators work in PHP. It's not overly complicated, but knowing when to use strict vs loose comparison makes a big difference in your code's reliability.</p>

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