php - substr 前两个字母在数组中匹配不起作用

Question

我有一个从输入字段生成的字符串，我想检查前两个字符并查看是否在数组中找到它们。如果是，我希望显示一条消息。

谁能解释为什么这不起作用？

$i = strtoupper($_POST['postcode']);
    $ep = array("AB", "BT", "GY", "HS", "IM", "IV", "JE", "PH", "KW");

    if (isset($i)) {

    if(substr($i, 0, 2) === in_array($i, $ep)) {
        echo "Sorry we don't deliver to your postcode";
    }   
}

Answer 1

你误解了 in_array 的工作原理，检查 manual了解更多详情。

以下代码是检查给定邮政编码是否有效的改进方法

<?php
/**
 * Check if the given post code is valid
 * @param string $postcode 
 * @return boolean
 */
function is_valid_postcode( $postcode = '' )
{
    $ep = array("AB", "BT", "GY", "HS", "IM", "IV", "JE", "PH", "KW");
    $postcode = strtoupper( $postcode );
    return in_array( $postcode , $ep );
}

if( isset( $_POST['postcode'] ) ){

    // Remove unwanted spaces if they're there
    $postcode = trim( $_POST['postcode'] );

    // Extract only the first two caracters
    $postcode = substr($postcode, 0, 2 );

    // Check if the submitted post code is valid
    if( !is_valid_postcode( $postcode ) ){
        echo "Sorry we don't deliver to your postcode";
    }
}