如何检查字符串是否包含存储在数组中的字符，但如果字符串包含不在数组中的任何字符，则返回false

Question

Basically I'm checking days of the week from an array to a string based on an initialization of the day for instance:

<?php
$check_days = array("M", "T");
$days1 = "MTW";
$days2 = "M";
[insert code to compare $check_days to $days1 and $days2 so that $days1 returns FALSE while $days2 returns TRUE]
?>

Answer 1

Try using a regex character class and implode:

if (preg_match('/^['.implode($check_days).']+$/', $days1)) {
    // do some stuff
}

EDIT: Let me help explain what's going on here:

implode($check_days)

This combines all the elements of an array into a single string. In your case, this is "MT".

preg_match('/^[MT]+$/', $days1);

This is a regular expression that checks that after the 'beginning' (^), $days1 contains either an "M" or a "T" ([MT]), repeated one or more times (+), then the string ends ($). It returns true if this is the case.

Hope that helps.