How to filter string in php to only get numbers

Obtaining method: 1. Use the for statement to loop through the string, use the is_numeric() function in the loop body to extract the numeric characters and use the ".=" operator to splice them into a new string. 2. Use regular expressions and use the "preg_replace("/[^0-9]/", "", $str)" statement.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Method 1: Using is_numeric() Function

<?php
header("content-type:text/html;charset=utf-8");
function findNum($str) {
	$str = trim($str);
	if (empty($str)) {
		echo &#39;&#39;;
	}else{
		$result = &#39;&#39;;
		for ($i = 0; $i < strlen($str); $i++) {
			if (is_numeric($str[$i])) {
				$result .= $str[$i];
			}
		}
		echo $result;
	}
}
$str = &#39;0我是123456一段测试的字789符串0&#39;;
findNum($str);
?>

• uses a for loop to traverse the string $str, and uses the is_numeric() function to determine whether $str[$i] is a numeric character. The is_numeric() function can detect whether a variable is a number or a numeric string.

• Use is_numeric($str[$i]) in the loop body to determine whether the $str[$i] character is a numeric character; if so, take it out and use ".= ” spliced ​​into digital substrings.

Look at the output:

01234567890

Method 2: Use preg_replace() function

<?php
$str =&#39;0我是123456一段测试的字789符串0&#39;;
$result = preg_replace("/[^0-9]/", "", $str);
echo $result;
?>

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