问正则表达式检查字符串是否包含

EN

$var = "stackoverflow";

if(preg_match('/[A-Z]|[a-z]|[0-9]|[.,$_]/', $var)) {
    echo "Matched";
}
else {
    echo "do not match";
}

$var = "stackoverflow";

if( (preg_match('/[A-Z]{1}/', $var) &&
     preg_match('/[a-z]{1}/', $var) &&
     preg_match('/[0-9]{1}/', $var) &&
     preg_match('/[.,$_]{1}/', $var)) ) {
    echo "String matches and contains at least one character from each group.";
}
elseif(preg_match('/[A-Z]|[a-z]|[0-9]|[.,$_]/', $var)) {
    echo "String matches, but doesn't contain characters from all four groups.";
}
else {
    echo "String does not match.";
}