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In PHP development, it is often necessary to validate a variable's type to ensure data accuracy and program stability. The is_int() function is a highly useful tool for determining whether a value is of integer type. This article provides a detailed guide on using the is_int() function, common use cases, and important considerations.
is_int() is a built-in PHP function used to check whether a given variable is an integer. If the variable is an integer, the function returns true; otherwise, it returns false. Its syntax is as follows:
<span><span><span class="hljs-keyword">bool</span></span><span> </span><span><span class="hljs-title function_ invoke__">is_int</span></span><span>(</span><span><span class="hljs-keyword">mixed</span></span><span> </span><span><span class="hljs-variable">$value</span></span><span>)
</span></span>$value: The variable to check, which can be of any type.
Returns true if the variable is an integer;
Returns false if the variable is not an integer.
<span><span><span class="hljs-variable">$number</span></span><span> = </span><span><span class="hljs-number">10</span></span><span>;
<p></span>if (is_int($number)) {<br>
echo "$number is an integer.";<br>
} else {<br>
echo "<span class="hljs-subst">$number is not an integer.";<br>
}<br>
Output:
<span><span>10 is an integer.
</span></span><span><span><span class="hljs-variable">$number</span></span><span> = </span><span><span class="hljs-string">"10"</span></span><span>;
<p></span>if (is_int($number)) {<br>
echo "$number is an integer.";<br>
} else {<br>
echo "<span class="hljs-subst">$number is not an integer.";<br>
}<br>
Output:
<span><span>10 is not an integer.
</span></span>Although "10" looks like an integer, it is a string, so is_int() returns false.
<span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-number">5</span></span><span> + </span><span><span class="hljs-number">3</span></span><span>;
<p></span>if (is_int($result)) {<br>
echo "The calculation result is an integer.";<br>
}<br>
</span>Output:
<span><span>The calculation result is an integer.
</span></span>Input Validation: Ensure user input is an integer to prevent type errors from crashing the program.
Data Processing: Confirm data is an integer before performing mathematical operations or database queries.
Conditional Logic: Branch logic based on variable type to improve code robustness.
In PHP, is_int(), is_integer(), and is_long() are functionally equivalent; they all check if a variable is an integer, just with different names:
<span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">is_int</span></span><span>(</span><span><span class="hljs-number">100</span></span><span>)); </span><span><span class="hljs-comment">// true</span></span><span>
</span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">is_integer</span></span><span>(</span><span><span class="hljs-number">100</span></span><span>)); </span><span><span class="hljs-comment">// true</span></span><span>
</span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">is_long</span></span><span>(</span><span><span class="hljs-number">100</span></span><span>)); </span><span><span class="hljs-comment">// true</span></span><span>
</span></span>These functions are interchangeable, but it is recommended to use is_int() for its concise and clear name.
is_int() does not perform automatic type conversion. A numeric string will return false even if its content represents an integer.
If you want to check if a value “looks like an integer,” you can use is_numeric() or convert it to an integer before checking.
<span><span><span class="hljs-variable">$input</span></span><span> = </span><span><span class="hljs-string">"42"</span></span><span>;
</span><span><span class="hljs-variable">$converted</span></span><span> = (</span><span><span class="hljs-keyword">int</span></span><span>)</span><span><span class="hljs-variable">$input</span></span><span>;
<p></span>if (is_int($converted)) {<br>
echo "The value is an integer after conversion.";<br>
}<br>
</span>Output:
<span><span>The value is an integer after conversion.
</span></span>is_int() is a simple yet very practical function in PHP that helps developers quickly determine whether a value is an integer. When writing programs that require strict type control, using is_int() can significantly enhance code robustness and safety. Mastering its usage and applying it flexibly in real scenarios is an essential skill for every PHP developer.
