未定义的索引 - 如何正确设置？

Question

具有此功能，成员电子邮件echo返回未定义的索引。我如何以正确的方式设置这个？

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;
    }
}

Answer 1

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
}

Answer 2

您可以在echo custom post index

之前使用！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;
    }
}