Skip first line using System.IO.File.ReadAllLines(fil) in C#

Question

I have a statement like:

string[] lines = System.IO.File.ReadAllLines(file);
foreach (string line in lines)
{
      ...
}

which causes me error as there is a header in the underlying .csv file. I want to skip this row, but when I use:

string [] lines = System.IO.File.ReadLines(file).Skip(1).ToArray();

yields me that String cannot use Skip(1). The same thing when I try to use:

string[] lines = System.IO.File.ReadAllLines(file);
lines = lines.Skip(1).ToArray();

yields me the same error.

Does anyone have any idea? Can I adjust the Foreach loop to become a For loop where I dismiss the first row?

Regards,

EDIT

The code I use as of now is:

    string[] lines = System.IO.File.ReadAllLines(file);
    lines = lines.Skip(1).ToArray();

   foreach (string line in lines)
    {
            var cols = line.Split(';');
            if (cols.Length == 1)
                continue;
            DataRow dr = tbl.NewRow();
            dr[0] = file;
            for (int cIndex = 1; cIndex + 1 < tbl.Columns.Count; cIndex++)
            {
                dr[cIndex + 1] = cols[cIndex];
            }
    }
    System.Text.StringBuilder b = new System.Text.StringBuilder();
    foreach (System.Data.DataRow r in tbl.Rows)
    {
        foreach (System.Data.DataColumn c in tbl.Columns)
        {
            b.Append(c.ColumnName.ToString() + ":" + r[c.ColumnName].ToString());
        }
    }
    MessageBox.Show(b.ToString());
    return tbl;

here the b.ToString() returns Nothing (as in NULL). Earlier when I used the GetAllLines() it returned:

fileName:fileNameStore:storeQuantity:quantityfileName:fileNameStore:1000Quantity:30

and it goes on like that.

My ideas are that perhaps I've made it so that I only imported one big long string, so when I skip the first line, it gets NULL.

But this is my first C# code ever, so I'm having some difficulties figuring this out.

Solution 1

there is no problem with your current algorithm:

string[] lines = System.IO.File.ReadAllLines(file);
lines = lines.Skip(1).ToArray();

just ensure you import the namespace below.

using System.Linq;

Solution 2

I would use the File.ReadLines() instead of the File.ReadAllLines().Because it is lazy loading the file. U'd rather not use the .ToArray() or the .ToList() as it would persist the whole file into the memory.

This will stream the data.

foreach(var line in File.ReadLines(file).Skip(1))
{

}

Will do the job...

Solution 3

Okay so extending my comment with some code sample and more descriptive explanation. I would suggest you to use StreamReader :

using ( StreamReader reader = new StreamReader(File.OpenRead(filePath)) )
{

Now ignore first line :

    reader.ReadLine();

And proceed with your reading logic :

    string line = string.Empty;
    while ( ( line =  reader.ReadLine() ) != null )
    {
        // your logic
    }
}

If you need to "pack" these lines into array you can just create a List<string> at the beginning and inside your logic use List<string>.Add(string) method with line as your string parameter. Then you can use List<string>.ToArray() method to return array of lines.

Solution 4

This can also be achieved by a single of code as:

var lines = File.ReadAllLines(csv_file_path).Skip(1).Select(a => a.Split(';',',')).ToList();

Solution 5

You could just do this, its not pretty but it will work :)

string[] lines = System.IO.File.ReadAllLines(file);
bool first = true;
foreach (string line in lines)
{
    if(!first)
    {
       ...
    }
    first = false;
}

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