Question

I have a simple application that has richTextBox and button.
User enters numbers(integers) into richTextBox (one number per line).

When He click the button I want to generate a sql query.

Basically it works if I pass integers into query like this:

SELECT price from products where ID IN (1, 2, 3, 4)

This is when user inputs 1,2,3,4 as lines in richTextBox.

But I would like pass binary(8) instead of integers.

This is my original line of code:

cmdString += " IN (" + string.Join(", ", richTextBox1.Lines) + ") ";

I have tried to change it with LINQ like this:

cmdString += " IN ("
+ string.Join(", ", richTextBox1.Lines.Select(c => 
    { c = "0x"+Convert.ToString(Convert.ToInt32(c), 16); 
     return c; 
    }).ToArray())
+ ") ";

What I would like to get:

For example convert:

 1   to  0x0000000000000001
30   to  0x000000000000001E

I hope You get the point.

Update:

I’ve done this:

textBox1.Text = string.Join(", ", richTextBox1.Lines.Select(c =>
    {
        c = "0x" + "0000000000000000".Substring(0, (16 - Convert.ToString(Convert.ToInt32(c), 16).Length)) + Convert.ToString(Convert.ToInt32(c), 16);
        return c;
    }).ToArray());

Any ideas how to remove second Convert.ToString(Convert.ToInt32(c)) usage? Or maybe do it in another way?

Answer 1

I’ll do this in foreach loop:

var query = "Select ... In( ";

foreach(var item in Lines)
{
   int a = 0;
   if (!int.TryParse(item, out a))
     throw new IllegalInputException();
   query += "0x" + Convert.ToString(a, 16).PadLeft(16, '0');
}
...

Or you can do it in your linq query but not easy to read as foreach one:

cmdString += " IN (" 
+ string.Join(", ", richTextBox1.Lines.Select(c => 
    { c = "0x"+Convert.ToString(Convert.ToInt32(c), 16)
               .PadLeft(16, '0'); 
     return c; 
    }).ToArray())  

+ ") ";