我想从文件中检索数据

Question

When I enter Id card number or phone number, it should fetch the line from file if Id or phone number matches. I have tried the following code but it fetches the id number & not the whole line with this Id card number eg name, address, phone number.

string path=@"C:\Users\Precision\Desktop\testing\data.txt";
Console.WriteLine("Enter CNIC or Phone No");
string check = Console.ReadLine();
using (StreamReader sr = new StreamReader(path))
{
    string lines = sr.ReadToEnd();

    if (lines.Contains(check))
    {
        dirList.Add(lines);
        Console.WriteLine("Data Found Against {0}", check);

        string stringToSearch = check;
        string[] liness = File.ReadAllLines(path);
        foreach (string line in liness)
        {
            if (line.Contains(stringToSearch))
            {
                Console.WriteLine(line);
            }
        }
    }
    else
    {
        Console.WriteLine("No Data Found");
    }
}

Example Data:

Id Card No :123456789 Phone No :545454 First Name :asasa Surname:asasa House:sas Street:as Sector:as City:asasas Country :asasa

Answer 1

1st you should simplify your code, eg actually you're reading the same file twice ( sr.ReadToEnd() , File.ReadAllLines(path) ). Then you should try to output ALL the lines (or better: inspect them in a debugger) to check if the data is actually in the format you expect. And additionally you have to decide if your entered search string check should actually be searched case sensitive or not.

Answer 2

The logic will depend on how you delimit each data item.
If each item is separated by a new line (ie \\r\\n ) then you should iterate as follows:

public List<string> SearchList()
{
    var path = @"C:\Users\Precision\Desktop\testing\data.txt";

    Console.WriteLine("Enter CNIC or Phone No");
    var check = Console.ReadLine();

    var dirList = new List<string>();

    using (StreamReader sr = new StreamReader(path))
    {
        var lines = sr.ReadToEnd()
                      .Split(new string[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries);

        foreach (var line in lines)
        {
            if (line.Contains($"Id Card No :{check}") || line.Contains($"Phone No :{check}"))
            {
                dirList.Add(line);
            }
        }
    }

    return dirList;
}

Notice the .Split() function. This will need to be adjusted depending on how your data is separated.

Also note how you will need to differentiate between "Id Card No :" and "Phone No :" to have some kind of intelligence in your search in case the text you search for happens to be in a different field.

If this list is large I would strongly recommend putting this data in a database and using a SQL query to search the items appropriately as databases are optimized to search for data items.

String searches are generally slow processing, and the sr.ReadToEnd() will put ALL the data in memory. If the file is huge, the memory that your application will consume can be quite large.

Answer 3

You can try using Linq in order to query the file. Often, file reading is a time consuming operation, that's why let's do it just once. In case you want to represent record in some custom format (ie Console.WriteLine(record); is not enough), you have to parse it, eg with a help of regular expressions .

Code:

    using System.Linq; 
    using System.Text.RegularExpressions;
    ... 
    string path = @"C:\Users\Precision\Desktop\testing\data.txt";

    Console.WriteLine("Enter CNIC or Phone No");
    string check = Console.ReadLine();

    var records = File
      .ReadLines(path)
      .Where(line => line.Contains(check));

    Regex regex = new Regex(@"(?<name>[^:]+):\s*(?<value>\S*)");

    bool isFirstRecord = true; 

    foreach (string record in records) {
      if (isFirstRecord)
        Console.WriteLine("Data Found Against {0}", check);

      isFirstRecord = false;

      Dictionary<string, string> data = regex
        .Matches(record)
        .Cast<Match>()
        .ToDictionary(match => match.Groups["name"].Value.Trim(),
                      match => match.Groups["value"].Value.Trim(),
                      StringComparer.OrdinalIgnoreCase);

      Console.WriteLine(string.Join(Environment.NewLine, data
        .Select(pair => $"{pair.Key,-11} = {pair.Value}")));  
    }

    // If we haven't read any record 
    if (isFirstRecord) 
      Console.WriteLine("No Data Found");

Outcome:

Data Found Against 12345
Id Card No  = 123456789
Phone No    = 545454
First Name  = asasa
Surname     = asasa
House       = sas
Street      = as
Sector      = as
City        = asasas
Country     = asasa

If you want some specific output format, you can easily query data dictionary, eg

Console.WriteLine($"Id: {data["Id Card No"]}; Phone: {data["Phone No"]}");