[英]How to use LINQ to return substring of FileInfo.Name
I would like to convert the below "foreach" statement to a LINQ query that returns a substring of the file name into a list: 我想将下面的“foreach”语句转换为LINQ查询,该查询将文件名的子字符串返回到列表中:
IList<string> fileNameSubstringValues = new List<string>();
//Find all assemblies with mapping files.
ICollection<FileInfo> files = codeToGetFileListGoesHere;
//Parse the file name to get the assembly name.
foreach (FileInfo file in files)
{
string fileName = file.Name.Substring(0, file.Name.Length - (file.Name.Length - file.Name.IndexOf(".config.xml")));
fileNameSubstringValues.Add(fileName);
}
The end result would be something similar to the following: 最终结果将类似于以下内容:
IList<string> fileNameSubstringValues = files.LINQ-QUERY-HERE;
Try something like this: 尝试这样的事情:
var fileList = files.Select(file =>
file.Name.Substring(0, file.Name.Length -
(file.Name.Length - file.Name.IndexOf(".config.xml"))))
.ToList();
IList<string> fileNameSubstringValues =
(
from
file in codeToGetFileListGoesHere
select
file.Name.
Substring(0, file.Name.Length -
(file.Name.Length - file.Name.IndexOf(".config.xml"))).ToList();
Enjoy =) 享受=)
If you happen to know the type of the collection of FileInfo
s, and it's a List<FileInfo>
, I'd probably skip the Linq and write: 如果您碰巧知道
FileInfo
集合的类型,并且它是List<FileInfo>
,我可能会跳过Linq并写:
files.ConvertAll(
file => file.Name.Substring(0, file.Name.Length - (file.Name.Length - file.Name.IndexOf(".config.xml")))
);
or if it's an array: 或者如果它是一个数组:
Array.ConvertAll(
files,
file => file.Name.Substring(0, file.Name.Length - (file.Name.Length - file.Name.IndexOf(".config.xml")))
);
Mainly because I like saying "Convert" instead of "Select" to express my intent to a programmer reading this code. 主要是因为我喜欢说“转换”而不是“选择”来表达我对程序员阅读此代码的意图。
However, Linq is part of C# now, so I think it's perfectly reasonable to insist that a reading programmer understand what Select
does. 但是,Linq现在是C#的一部分,所以我认为坚持阅读程序员理解
Select
作用是完全合理的。 And the Linq approach lets you easily migrate to PLinq in the future. Linq方法可让您在将来轻松迁移到PLinq。
FYI, 仅供参考,
file.Name.Substring(0, file.Name.Length - (file.Name.Length - file.Name.IndexOf(".config.xml")))
is the same as 是相同的
file.Name.Substring(0, file.Name.IndexOf(".config.xml"));
Also, if that string ".config.xml" appears before the end of the file name, your code will probably return the wrong thing; 此外,如果该字符串“.config.xml”出现在文件名末尾之前,那么您的代码可能会返回错误的内容; You should probably change IndexOf to LastIndexOf and check that the index position returned + 11 (the size of the string) == length of the filename (assuming you're looking for files ending in .config.xml and not just files with .config.xml appearing somewhere in the name).
您应该将IndexOf更改为LastIndexOf并检查索引位置是否返回+ 11(字符串的大小)==文件名的长度(假设您正在查找以.config.xml结尾的文件而不仅仅是.config文件.xml出现在名称的某处)。
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