Add column in position number two in csv file in c#

Question

I have a lot of different CSV files with data in it (including headers).

I can't figure it out how to add a new column in the position number two.

I can fill the new cell with the null value (each row) but the new column is in first position.

Please see attachment image : the new column it must be after the column IDINTA.

Can anybody help me?

Thanks in advance

My code below.

output = System.Web.HttpContext.Current.Server.MapPath("/public/target.csv");

string[] CSVDump = File.ReadAllLines(output);
List<List<string>> CSV = CSVDump.Select(x => x.Split('|').ToList()).ToList();
for (int i = 0; i < CSV.Count; i++)
{
    CSV[i].Insert(0, i == 0 ? "Headername" : "Filename");
}
File.WriteAllLines(output, CSV.Select(x => string.Join("|", x)));

#Edit 01

#Edit 02

N|IDINTA|Filename|DDMMYYYY HHMMSS|

The way I can think of is; to convert csv to DataTable. Once data is there in DataTable, you can add column at whatever position you want. — A3006
– A3006, Commented Feb 17, 2017 at 13:48
So which of the columns is the one you want to insert? Can you show us what it should look like before and after? — wkl
– wkl, Commented Feb 17, 2017 at 13:59
Can you please explain which of csv tables is before, which is after and what the third one is? — wkl
– wkl, Commented Feb 17, 2017 at 14:07
@wkl : I need add new column Filename in csv file between column IDINTA and DDMMYYYY HHMMSS — Antonio Mailtraq
– Antonio Mailtraq, Commented Feb 17, 2017 at 14:08

wkl · Accepted Answer · 2017-02-17 14:24:46Z

2

Simply change the index in your Insert statement:

CSV[i].Insert(2, i == 0 ? "Headername" : "Filename");

Using a variable for the desired position, the complete code would be:

// define the desired position here:
int posNewColumn = 2;

output = System.Web.HttpContext.Current.Server.MapPath("/public/target.csv");

string[] CSVDump = File.ReadAllLines(output);
List<List<string>> CSV = CSVDump.Select(x => x.Split('|').ToList()).ToList();
for (int i = 0; i < CSV.Count; i++)
{
    if( CSV[i].Count > posNewColumn)
    {
        CSV[i].Insert(posNewColumn , i == 0 ? "Headername" : "Filename");
    }
    else 
    {
    // append the new data at the end if the existing line is too short.
    // You may want to do nothing instead or fill the appropriate number
    // of empty cells before adding.
        CSV[i].Add(i == 0 ? "Headername" : "Filename");
    }
}
File.WriteAllLines(output, CSV.Select(x => string.Join("|", x)));

edited Feb 17, 2017 at 14:24

answered Feb 17, 2017 at 13:52

wkl

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4 Comments

Antonio Mailtraq Over a year ago

Thank you for help. please see #Edit 01 in my first question

wkl Over a year ago

@AntonioMailtraq If you get an error that the index must be within the limits of the list, I assume that there is a line in your csv which is shorter than the others. You should check for that. If this is a requirement, add it to the question.

Antonio Mailtraq Over a year ago

it's possible that there is a line in your csv which is shorter than the others, but are hundreds of rows

wkl Over a year ago

edited. When the line is not long enough, we append it at the end of the line.

kemiller2002 · Accepted Answer · 2017-02-17 14:19:49Z

0

This should do it.

output = System.Web.HttpContext.Current.Server.MapPath("/public/target.csv");

string[] CSVDump = File.ReadAllLines(output);

var CSV = CSVDump.Select(x => x.Split('|').ToList());

var newInserted = CSV.Aggregate(new List<List<String>>(), (l, i) =>
{
    i.Insert(1, (l.Count == 0) ? "header" : "fileName");
    l.Add(i);
    return l;
});

File.WriteAllLines(output, newInserted.Select(x => string.Join("|", x)));

edited Feb 17, 2017 at 14:19

answered Feb 17, 2017 at 13:54

kemiller2002

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9 Comments

Antonio Mailtraq Over a year ago

Thanks, but with your code the new column is not added.

kemiller2002 Over a year ago

lemme check, then, it's not appearing in the newInserted variable?

kemiller2002 Over a year ago

oops should be fixed now.

Antonio Mailtraq Over a year ago

Thanks, the new column is not added

kemiller2002 Over a year ago

are you looking the CSV variable for the new column?

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