使用文件读取将整数添加到列表或数组

Question

I have a .txt file with some numbers

File:
1
2
3
4

I would like to have a method that reads those numbers and adds them to a list or array which will show it in a messagebox.

I have this at the moment:

public void LaadVrijeKamers()
        {
            int KamerNummers = Convert.ToInt32(File.ReadAllText(@"x\Vrijekamers.txt"));
            MessageBox.Show(Convert.ToString(KamerNummers));
        }

I am getting an error in Dutch that says the following:

Can not read the characters

I think the File.ReadAllText is only for Strings, but I am not sure. Maybe I am converting wrong.

Answer 1

尝试逐行阅读并将字符串转换为整数：

var numbers = File.ReadLines(@"C:\path\numbers.txt").Select(int.Parse).ToList();

Answer 2

File.ReadAllLines() returns an array of strings. Convert.ToInt32 takes a single string.

You need to iterate over each string in the file and convert them one at a time.

Answer 3

File.ReadAllText fails because it returns all the text, which is not convertible to an integer. You should try something like the following:

int intList = File.ReadAllLines()
                  -- get only lines with numbers
                  .Where(l => {
                      int val;
                      bool isOk = int.TryParse(l, out value);
                      return isOk;
                  }
                  -- actual conversion
                  .Select(l => Convert.ToInt32(l)
                  .ToList();

Answer 4

Well, you can use a combination of LINQ methods here :

    public void LaadVrijeKamers()
    {
        var KamerNummers =    File.ReadAllLines(@"x\Vrijekamers.txt")
                              .Skip(1)                      //Skips file header (if needed)
                              .Select(Int32.Parse)          //Converts to int
                              .ToList();                    //Returns List

        // To display numbers we'd first have to create a string from our list
        MessageBox.Show(string.Concat(KamerNummers.Select(n => n.ToString() + ", ")));
    }

Answer 5

Without Linq query

var rows = File.ReadAllText(@"x\Vrijekamers.txt");
var strnumbers = rows.Split(new string[] { "\r\n" }, StringSplitOptions.None);

var ListOfNumber = new List<int>();

foreach (string number in strnumbers)
{
    int num = 0;

    if(int.TryParse(number, out num))
        ListOfNumber.Add(num);
}