从csv文件中提取特定列

Question

When I run this code it takes 11 elements in the first iteration. In the second iteration it's reduced to 6 elements and in the last it takes 1 element and then shows an "array out of range exception".

What am I doing wrong?

foreach (string line in File.ReadLines(Path))
{  
    string [] column = line.Split(',');
    if (id == column[4])
    {
        return false;
    }
    Array.Clear(column, 0, column.Length);
}

Answer 1

If you say line has only 1 element on the 3rd iteration, then you make column = line.Split(','), column will have 1 element. so at that point column[4] is "out of range" as the string array only has one element in it.

What exactly are you trying to do with this though, so we can give you an answer better than just the exception.

edit: So by your comment all you have to do is see if the 5th column matches what's in id and return false if so?

foreach (string line in File.ReadLines(Path))
{  
    string [] column = line.Split(',');
    if (column.Count() >= 5 && column.id == column[4])
    {
        return false;
    }
}

this will ensure you have at least 5 elements in your column array before you try to access the 5th element column[4] in the == check.

Answer 2

Have you tried making sure that the row being check has enough columns ?

By 4th column you mean the column at index 4 ? or you mean the 4th column which is at index 3 ?

private bool SomeMethod(String path, String id)
{
    string [] column ;

    foreach (string line in File.ReadLines(Path))
    {  
        column = line.Split(',');

        //check that there are at least 5 columns before comparing it with ID
        if ((column.Length >= 5) && (id == column[4]))
        {
            return false;
        }
    }
}