Use PHP function "is_numeric" to check if a variable is of numeric type

Use the PHP function "is_numeric" to check whether a variable is of numeric type

In PHP, we often need to check whether a variable is of numeric type. In order to achieve this function, PHP provides a built-in function "is_numeric". This article will introduce the usage of is_numeric function and some sample code.

The is_numeric function is used to determine whether a variable is of numeric type. It accepts a parameter, the variable to be judged, and returns a Boolean value. Returns true if the variable is of numeric type; returns false if the variable is not of numeric type.

The following is the syntax of the is_numeric function:

bool is_numeric (mixed $var)

Among them, $var is the variable that needs to be judged. Can be an integer, floating point number or string. If the variable is a string, is_numeric will try to convert it to a numeric type and make a judgment.

The following is some sample code for the is_numeric function:

$num1 = 123;
$num2 = 1.23;
$str = "123";
$invalid = "abc";

var_dump(is_numeric($num1));   // 输出: bool(true)
var_dump(is_numeric($num2));   // 输出: bool(true)
var_dump(is_numeric($str));    // 输出: bool(true)
var_dump(is_numeric($invalid)); // 输出: bool(false)

In the above sample code, we defined four variables: $num1, $num2, $str and $invalid.

$num1 is a variable of integer type, $num2 is a variable of floating point type, $str is a variable of numeric string type, and $invalid is a variable of non-numeric string type.

By calling the is_numeric function and passing these four variables as parameters, we can see the corresponding output results.

As you can see from the results, $num1, $num2, and $str are judged to be numeric types, and true is returned. $invalid was judged to be a non-numeric type and false was returned.

It should be noted that the is_numeric function will also return false for empty strings or pure white space strings.

In addition to using the is_numeric function, we can also use other methods to determine whether a variable is of numeric type. For example, use the is_int function to determine whether a variable is of integer type, and use the is_float function to determine whether a variable is of floating-point type.

Summary:

Through the introduction of this article, we have learned how to use PHP's built-in function is_numeric to determine whether a variable is of numeric type. The is_numeric function is simple and easy to use, and is suitable for various types of variable judgments. I hope this article will help you understand the usage of is_numeric function.

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