循环中创建的分隔字符串 [英] Separated string created in loop

问题描述

我正在寻找创建循环中另一个字符串的最佳方法.我的意思是，例如，SQL阅读器:

I'm searching the best way to create a string separated with another in a loop. I mean, for example, SQL reader:

StringBuilder sb = new StringBuilder();
while(reader.Read())
{
  sb.Append(reader[0]);
  sb.Append("<br />");
}
string result = sb.ToString();
result = result.Remove(result.LastIndexOf("<br />")); // <-

或创建SQL查询字符串；

or creating SQL query string;

StringBuilder sb = new StringBuilder();
foreach(string v in values)
{
  sb.Append(v);
  sb.Append(",");
}
string query = sb.ToString()
query = query.Remove(query.LastIndexOf(",")); // <-
query = String.Concat("INSERT INTO [foo] ([bar]) VALUES(", query, ")");

这是我发现的最好的

List<string> list = new List<string>;
while(reader.Read())
{
  list.Add(reader[0]);
}
string result = String.Join("<br />", list.ToArray());

我了解StringBuilder，在这里我只是为了清楚起见而没有使用它.我的一般想法不使用Remove/LastIndexOf！

I know about StringBuilder, I didn't used it here just for some clarity. My general idea do not use Remove / LastIndexOf !

推荐答案

除非您真的知道需要担心性能，否则我不喜欢StringBuilder.它产生难看的代码.我会这样写...

I am not a fan of StringBuilder unless you really know that you need to worry about performance. It produces ugly code. I would write it this way...

private IEnumerable<string> ReadAllStrings(DataReader reader)
{
    while(reader.Read())
        yield return reader[0];
}


String.Join("<br />", ReadAllStrings(reader).ToArray());

如果我经常这样做，我可能会考虑一种扩展方法:

If I were doing it a lot, I might consider an extension method:

public static class Extensions
{
    public static string JoinWith(this IEnumerable<string> strings, string separator)
    {
        return String.Join(separator, strings.ToArray());
    }
}

然后，我的代码如下所示:

Then, my code would look like this:

ReadAllStrings(reader).JoinWith("<br />");

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