PHP | is_numeric() Function

The is_numeric() function is an inbuilt function in PHP which is used to check whether a variable passed in function as a parameter is a number or a numeric string or not. The function returns a boolean value.

Syntax: 

bool is_numeric ( $var )

Parameters: The function accepts a single parameter which is mandatory and described below: 

• $var: This input parameter is the variable which the function checks for whether it is a number or a numeric string. Based on this verification, the function returns a boolean value.

Return Value: The function returns TRUE if $var is a number or a numeric string and returns FALSE otherwise.

Examples:  

Input : $var = 12
Output : True

Input : $var = "Geeks for Geeks"
Output : False

Below programs illustrate the is_numeric() function:

Program 1: In this program, a number is passed as input.  

<?php

$num = 12;
if (is_numeric($num)) {
        echo $num . " is numeric";
    }
    else {
        echo $num . " is not numeric";
    }

?>

12 is numeric

Program 2: In this program, a string is passed as input. 

<?php

$element = "Geeks for Geeks";
if (is_numeric($element)) {
        echo $element . " is numeric";
    }
    else {
        echo $element . " is not numeric";
    }

?>

Geeks for Geeks is not numeric

Program 3: In this program, a numeric string is passed as input. 

<?php

$num = "467291";
if (is_numeric($num)) {
        echo $num . " is numeric";
    }
    else {
        echo $num . " is not numeric";
    }

?>

467291 is numeric

Program 4:

<?php
$array = array(
    "21/06/2018",
    4743,
    0x381,
    01641,
   0b1010010011,
    "Geek Classes"
);

foreach ($array as $i) {
    if (is_numeric($i)) {
        echo $i . " is numeric"."\n";
    } else {
        echo $i . " is NOT numeric"."\n";
    }
}
?>

21/06/2018 is NOT numeric
4743 is numeric
897 is numeric
929 is numeric
659 is numeric
Geek Classes is NOT numeric

Reference: https://www.php.net/manual/en/function.is-numeric.php