如何从 C# 中包含特定 Substring 的字符串数组返回字符串？

Question

I am taking string array of arguments of command line and checking if there is any argument which contains a ".xml" substring

string[] args = this.Command.GetCommandLineArgs();
string strXMLFileName = string.Empty;
for (int i = 0; i < args.Length; ++i)
{
    if (args[i].Contains(".xml"))
    {
        strXMLFileName = args[i];
    }
}

I searched a bit in List<string> methods, but couldn't find anything that could simplify the process

I am assuming there is only 1 argument with ".xml" substring

Is there any built-in C# method with which I can do this without manually iterating through the string array

Answer 1

You can use LINQ :

var strXMLFileName = args.FirstOrDefault(x => x.Contains(".xml"));

Will yield null is there is no such argument.

---

NB: For the search string ".xml" , EndsWith is usually more appropriate than Contains .

Answer 2

You can try SingleOrDefault() , so that you will get an exception if there are multiple .xml files are available in the list. I used EndsWith() instead of Contains() , so that condition will check file ends with .xml or not.

var strXMLFileName = args.SingleOrDefault(x => x.EndsWith(".xml")) ?? string.Empty;

Answer 3

If you are sure that string with .xml is in array:

var arr = new string[]
{
    "file1.txt",
    "file2.xml",
    "file3.xml",
};

var strXMLFileName = arr.First(x => x.EndsWith(".xml"));

System.Console.WriteLine(strXMLFileName);

If you are not sure:

var arr = new string[]
{
    "file1.txt",
    "file2.xml",
    "file3.xml",
};

var strXMLFileName = arr.FirstOrDefault(x => x.EndsWith(".xml"));

System.Console.WriteLine(strXMLFileName);