Php 未定义索引-如何正确设置？

具有此功能，成员电子邮件回送返回未定义的索引。我该如何正确地设置它

function team_custom_columns( $column ) {
    global $post;
    switch ( $column )
    {

        case 'member_email':
            $custom = get_post_custom();
            echo $custom['member_email_address'][0];
            break;
        case 'member_description':
            the_content();
            break;
    }
}

---

使用三元运算符：

echo isset($custom['member_email_address'][0])
     ? $custom['member_email_address'][0]
     : 'not set';

或者如果：

if (isset($custom['member_email_address'][0])) {
    // value exists
} else {
    // not set
}

你可以用！echo自定义post索引之前的empty（）方法

function team_custom_columns( $column ) {
    global $post;
    switch ( $column )
    {

        case 'member_email':
            $custom = get_post_custom();
            if(!empty($custom['member_email_address'][0]))
                echo $custom['member_email_address'][0];
            break;
        case 'member_description':
            the_content();
            break;
    }
}

---

谢谢各位。这两个答案都很好，效果也很好。