将多行字符串添加到另一个字符串=丢失多行？

Question

I wish to create a string that contains a list of stuff with one item on each line, but the following code doesn't maintain the new lines:

foreach (DateTime date in dates)
{
    datelist += date.ToString("yyyy/MM/dd") + Environment.NewLine;
}

string mystring = String.Format(@"Hey there here is a list of dates

                                  Dates:

                                  {0}",
                                  datelist);

Output:

Hey there here is a list of dates

Dates:

2012/03/04 2012/03/05 2012/03/06

Desired output:

Hey there here is a list of dates

Dates:

2012/03/04

2012/03/05

2012/03/06

I tried variations, such as two Environment.NewLines, escapes like \\r\\n, starting the string with @, and so on, and I could not get my desired output.

I was ultimately able to solve my problem by putting a symbol into the string where I want linebreaks, and then use string.Replace to change the symbol to Environment.NewLine:

foreach (DateTime date in dates)
{
    datelist += date.ToString("yyyy/MM/dd") + "<br />";
}

string mystring = String.Format(@"Hey there here is a list of dates

                                  Dates:

                                  {0}",
                                  datelist.Replace(Environment.NewLine, "<br />"));

Like I said, this works, but I wish to know why good old concatenation doesn't work when inserting a string with lines into another string, as well as what the standard/common solution to my question would be.

Answer 1

If you render HTML output, you shouldn't use Environment.NewLine - use <br /> instead. Multiple consecutive whitespace (including \\r and \\n ) may be aggregated by the browser into a single whitespace. (Based on my experience, the actual behavior is somewhat browser dependent but I didn't actually research into this.)

foreach (DateTime date in dates)
{
    datelist += date.ToString("yyyy/MM/dd") + "<br />";
}

string mystring = String.Format("Hey there here is a list of dates<br />" +
    "Dates:<br />{0}", datelist);

If somewhere within the string you need multiple blank lines, use multiple <br /> -s, of course.