String interpolation and formatting a table-CodePudding

TL:DR:

For C# string interpolation, where does the <alignment> actually add spaces in {<interpolationExpression>,<alignment>}? Is it the rightmost character of the preceding string? Is it the leftmost character of the preceding string? How can I make a simple table like the one shown below?

Toy Example:

I am trying to understand how string spacing works with string interpolation in C#. Consider the below table.

Score:  97
Name:   Jack
ID:     01123

I have tried to replicate this simple example below and have also put digits for tracking spacing between the 2nd column and the 1st column. I don't have double digits for the spacing string, rather it is 1 through 9 followed by a 0 that represents 10. Then it is 1 through 9 again (representing 11-19 spaces) followed by another 0 (representing 20 spaces).

Console.WriteLine("12345678901234567890"); // For tracking spacing
Console.WriteLine($"Score: {97, 10}");
Console.WriteLine($"Name: {"Jack", 10}");
Console.WriteLine($"ID: {01123, 10}");

the output of which is

12345678901234567890
Score:         97
Name:       Jack
ID:       1123

The spacing for the line Score: ... 97 indicates that the spacing between 97 and Score: is based on the last character of Score:, which is :. I draw this conclusion based on the spacing string 6 at the : location and the spacing string 6 at the 9 location. However, the spacing for the line Name: ... Jack, the distance between the : in Name and J in Jack is 12.

I think one solution to deal with this alignment issue might be to use the String.Length property, but I am not sure. How does alignment work in C# string interpolation, and how can I use it to make a simple table like I have shown?

CodePudding user response：

The problem is the format still makes each value string the same length, but the initial field names are not the same length, and so your fixed-length values strings start from different places.

For this case, where the first column is static text and the second column is always left-justified, the extra format is not helpful because you can put in the spaces directly:

Console.WriteLine("12345678901234567890"); // For tracking spacing
Console.WriteLine($"Score:  {97}");
Console.WriteLine($"Name:   {"Jack"}");
Console.WriteLine($"ID:     {01123}");

But let's say you have data more like this:

var items = new List<(string, object)>  {
    ("Score", 97),
    ("Name", "Jack")
    ("ID",   1123)
};

You can handle that like by putting the padding on the leading field names, like so:

foreach(var item in items)
{
    Console.WriteLine($"{item.Item1,-10}{item.Item2}");
}

But this is still missing the : separator. You could restore it like this:

foreach(var item in items)
{
    Console.WriteLine($"{item.Item1 ':',-10}{item.Item2}");
}

The other thing potentially worth exploring here is a tab character, though that can be tricky if the variance between your field names is more than the width of the tab.