使用StringReader怎么样?

using (System.IO.StringReader reader = new System.IO.StringReader(input)) {
    string line = reader.ReadLine();
}

其实很简单。

VB。NET:

Private Function SplitOnNewLine(input as String) As String
    Return input.Split(Environment.NewLine)
End Function

C#:

string splitOnNewLine(string input)
{
    return input.split(environment.newline);
}

using System.IO;

string textToSplit;

if (textToSplit != null)
{
    List<string> lines = new List<string>();
    using (StringReader reader = new StringReader(textToSplit))
    {
        for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
        {
            lines.Add(line);
        }
    }
}

好吧，实际上拆分应该做:

//Constructing string...
StringBuilder sb = new StringBuilder();
sb.AppendLine("first line");
sb.AppendLine("second line");
sb.AppendLine("third line");
string s = sb.ToString();
Console.WriteLine(s);

//Splitting multiline string into separate lines
string[] splitted = s.Split(new string[] {System.Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries);

// Output (separate lines)
for( int i = 0; i < splitted.Count(); i++ )
{
    Console.WriteLine("{0}: {1}", i, splitted[i]);
}

根据Guffa的答案，在扩展类中使用:

public static string[] Lines(this string source) {
    return source.Split(new string[] { "\r\n", "\n" }, StringSplitOptions.None);
}

要拆分一个字符串，你需要使用一个字符串数组的重载:

string[] lines = theText.Split(
    new string[] { Environment.NewLine },
    StringSplitOptions.None
);

编辑: 如果要处理文本中不同类型的换行符，可以使用匹配多个字符串的功能。这将正确地拆分任意类型的换行，并保留文本中的空行和空格:

string[] lines = theText.Split(
    new string[] { "\r\n", "\r", "\n" },
    StringSplitOptions.None
);