C# 使用 string.format 和 List<T>.Count() 进行动态字符串格式化
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dynamic string formatting using string.format and List<T>.Count()
提问by Chris
I have to print out some PDFs for a project at work. Is there way to provide dynamic padding, IE. not using a code hard-coded in the format string. But instead based on the count of a List.
我必须为工作中的项目打印一些 PDF。有没有办法提供动态填充，IE。不使用在格式字符串中硬编码的代码。而是基于列表的计数。
Ex.
前任。
If my list is 1000 elements long, I want to have this:
如果我的列表有 1000 个元素，我想要这个：
Part_0001_Filename.pdf... Part_1000_Filename.pdf
Part_0001_Filename.pdf... Part_1000_Filename.pdf
And if my list is say 500 elements long, I want to have this formatting:
如果我的列表长度为 500 个元素，我希望采用以下格式：
Part_001_Filename.pdf... Part_500_Filename.PDF
Part_001_Filename.pdf... Part_500_Filename.PDF
The reason for this is how Windows orders file names. It sorts them alphabetically left-to-right or right-to-left, So I must use the leading zero, otherwise the ordering in the folder is messed up.
原因在于 Windows 如何对文件名进行排序。它按字母顺序从左到右或从右到左对它们进行排序，所以我必须使用前导零，否则文件夹中的排序会混乱。
采纳答案by Jon Skeet
The simplest way is probably to build the format string dynamically too:
最简单的方法可能也是动态构建格式字符串：
static List<string> FormatFileNames(List<string> files)
{
int width = (files.Count+1).ToString("d").Length;
string formatString = "Part_{0:D" + width + "}_{1}.pdf";
List<string> result = new List<string>();
for (int i=0; i < files.Count; i++)
{
result.Add(string.Format(formatString, i+1, files[i]));
}
return result;
}
This could be done slightly more simply with LINQ if you like:
如果您愿意，可以使用 LINQ 更简单地完成此操作：
static List<string> FormatFileNames(List<string> files)
{
int width = (files.Count+1).ToString("d").Length;
string formatString = "Part_{0:D" + width + "}_{1}.pdf";
return files.Select((file, index) =>
string.Format(formatString, index+1, file))
.ToList();
}
