如何检查数字是否有4位数字 - How to check if the number has 4 digital

How to check if the number has 4 digital

假设我有以下值，并且我想要年份

July 1967 USA
14 March 1979 France
23 June 1976 France
from the 21 October 2016

假设这个值是$year2，我正在使用is_numeric，但没有给出正确的结果，就像总是使用preg_replace 一样

            $year2 = explode(" ",$year1);
            if (!is_numeric($year2[2])) {
                if ( ! isset($year2[1])) {
                 $year2[1] = null;
                 }
            $year =  $year2[1];
            } else {
                 if ( ! isset($year2[2])) {
                 $year2[2] = null;
                 }
                $year =  $year2[2];
                }
            }
echo $year;

输出有时是ex:21日，而不是2016年我尝试了这个，但没有成功$year = preg_match('/'d{4}/g',$year2);

如果你想从每一行中获得年份(正如我理解你的问题(，你可以使用preg_match()

<?php
$values = [
    'July 1967 USA',
    '14 March 1979 France',
    '23 June 1976 France',
    'from the 21 October 2016',  
];
foreach ($values as $value) {
    $pattern = '/(^|'s)('d{4})('s|$)/m';
    preg_match($pattern, $value, $match);
    echo $match[2] . "'n";
}

输出：