c# - 显示字符串中的字符串列表

Question

好的，我在这里尝试向用户发送一封关于无效附件的电子邮件。我在之前的函数中收集了无效附件名称(字符串)的列表，然后我试图发送一封电子邮件，其中列出所有被视为无效的附件。不知道如何处理这种情况。我有下面的例子

List<string> invalidType = new List<string>();

if (invalidType != null)
{
    emailInvalidBody = new ItemBody
    {
        Content = " Expense attachements recieved with subject line [ "
           + email.Subject 
           + " ] sent at  [  " 
           + email.DateTimeReceived.Value.DateTime.ToLocalTime() 
           + " ] had the following invalid attachments [" 
           + invalidType 
           + "].  Please make sure all attachment's are images or PDF's.",
    };
}
List<Recipient> emailInvalidRecipients = new List<Recipient>();
emailInvalidRecipients.Add(new Recipient
{
    EmailAddress = new EmailAddress
    {
        Address = email.Sender.EmailAddress.Address
    }
});
Message invalidEmailMessage = new Message
{
    Subject = "Invalid Expenses",
    Body = emailInvalidBody,
    ToRecipients = emailInvalidRecipients
};
starBox.Users[EMAILBOX].SendMailAsync(invalidEmailMessage, false).Wait();

我的最终目标是拥有一个将执行以下操作的电子邮件正文

"Expense attachements recieved with subject line Subject sent at 8:00 1/29/16 had the following invalid attachments [ invalidattachment1 invalidattachment2 invalidattachment3 invalidattachment4 ]. Please make sure all attachment's are images or PDF's.",

Answer 1

使用 string.Join 转换您的 List<string>在所有项目连接在一起的列表中

List<string> invalidType = new List<string>();
.....

// Probably you don't need to check for null but for element count.
// However it doesn't hurt to be a little defensive...
if (invalidType != null && invalidType.Count > 0)
{
    string attachments = string.join(",", invalidType);
    emailInvalidBody = new ItemBody
    {
        Content = " Expense attachments received with subject line [ " + 
                  email.Subject + " ] sent at  [  " + 
                  email.DateTimeReceived.Value.DateTime.ToLocalTime() + 
                  " ]  had the following invalid attachments [" + 
                  attachments + "].  Please make sure all " + 
                  " attachment's are images or PDF's.",
    };

}