字符串和首字母索引的索引

Question

If i write 'a' in the run time , the program should display all the name starting with 'a' stored in a text file .

Whenever i write any letter, the names starting with that letter should be displayed.

string contents = File.ReadAllText("Data.txt");
foreach (var line in File.ReadLines("Data.txt")) ;

Answer 1

What I assume you mean is that you want to select only the lines from your fine (that each line represents a name) that begin with a given input (for example a )

string input = Console.ReadLine();

var result = File.ReadLines("data.txt").Where(line => line.StartsWith(input)).ToList();

to display all the names in one blow you can use:

Console.WriteLine(String.Join("\n", result));

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In the case each line in your file contains more than one name then you can split it like this: (For this example the way to separate between names is , ):

string input = Console.ReadLine();

var result = File.ReadLines("data.xml")
                 .SelectMany(line => line.Split(','))
                 .Select(name => name.Trim())
                 .Where(line => line.StartsWith(input)).ToList();