check if a vatiable contains number in php code example

Example 1: check if string is number or not php

$var_num = "1";
$var_str = "Hello World";

var_dump( is_numeric($var_num), is_numeric($var_str) );

/* 
Output -
 bool(true)
 bool(false)
*/

Example 2: how to check if PHP variable contains non-numbers?

if ( is_numeric($_POST['foo']) ) {
    $foo = $_POST['foo'];
} else {
    // Error
}