Unable to read from a CSV using List

Question

I have seen the following code used in other posts and it seems to be accepted as an answer but when I use it, it doesn't work correctly. Its purpose is to pull the last three lines of a text file and output them to the user.

I do not receive any build errors, but the console doesn't output the contents of the given .csv.

List<string> test = File.ReadAllLines("test.csv").Reverse().Take(3).Reverse().ToList();

Console.WriteLine(test);

EDIT:

This posted without the full post.

The contents of the csv are numbers 0-10 and I need to pull the last three numbers of the file upon request.

For testing purposes, the csv is currently laid out:

I want to pull the numbers in the order of 3, 4, 5.

It would appreciable if you could let us know how your csv looks like and what is the expected output. — Mohit S, Dec 14 '15 at 09:34
What is in the file? What is being printed to console? Create a [mcve]. — CodeCaster, Dec 14 '15 at 09:34
"it doesn't work correctly" What does this mean? What do get instead of the expected? — MakePeaceGreatAgain, Dec 14 '15 at 09:36
Follow Ryan Searle answer. With a foreach to write the list contents it works just fine — Pikoh, Dec 14 '15 at 09:55

score 1 · Answer 1 · answered Dec 14 '15 at 09:35

1

What you're WriteLineing is a value of List<string>.ToString(), which is not what you want. Try foreaching over the test list and WriteLine each line separately.

answered Dec 14 '15 at 09:35

Anton Gogolev

113,561
39
200
288

score 1 · Answer 2 · answered Dec 14 '15 at 09:35

1

foreach(var item in test )
{
Console.WriteLine(item);
}

answered Dec 14 '15 at 09:35

Bayu Alvian

171
5

score 0 · Accepted Answer · edited Dec 15 '15 at 07:11

0

Your example will print something like "System.Collections.Generic.List'1[System.String]" This is because the Console.WriteLine() is expecting a string (which it may be receive using the object's ToString() method) yet you pass it a List<> object whose ToString() method returns "System.Collections.Generic.List'1[System.String]".

Instead you need to retrieve each string from the list with a foreach loop and then print each string as you retrieve it.

For Example:

var lst = new List<string>();

lst.Add("test1");
lst.Add("test2");
lst.Add("test3");           

foreach (var item in lst)
{
    Console.WriteLine(item); // item, not list
}
Console.Read();

edited Dec 15 '15 at 07:11

benf

77
1
1
12

answered Dec 14 '15 at 09:41

Ryan Searle

1,597
1
19
30

This still outputs _"System.Collections.Generic.List'1[System.String]"_ though, any ideas? – benf Dec 14 '15 at 21:21
1

**Fixed** WriteLine is item, not lst. Code now working, thanks! – benf Dec 15 '15 at 05:35

score -1 · Answer 4 · edited May 23 '17 at 11:59

-1

You can do it like this:

using System.IO;

static void Main(string[] args)
{
    var reader = new StreamReader(File.OpenRead(@"C:\test.csv"));
    List<string> listA = new List<string>();
    List<string> listB = new List<string>();
    while (!reader.EndOfStream)
    {
        var line = reader.ReadLine();
        var values = line.Split(';');

        listA.Add(values[0]);
        listB.Add(values[1]);
    }

    foreach(var item in listA )
    {
       Console.WriteLine(item);
    }

    foreach(var item in listB )
    {
       Console.WriteLine(item);
    }
}

Link to the Answer

edited May 23 '17 at 11:59

Community

1
1

answered Dec 14 '15 at 09:38

ascholz

179
1
9

Don't copy answers. Don't parse CSV using `string.Split()`. – CodeCaster Dec 14 '15 at 09:39
Instead of copying the code of that related answer you may simply have flagged the question as a duplicate. – MakePeaceGreatAgain Dec 14 '15 at 09:40
ok thanks for the information. I dont copy code anymore. But I imporved the answere. And I only copy the code above without telling were it is from. – ascholz Dec 14 '15 at 09:43
See the OPs update. There is no need to split the lines within the file as only one item is contained per line. Thus your answer is obsolete. – MakePeaceGreatAgain Dec 14 '15 at 09:53

Unable to read from a CSV using List

4 Answers4