Formatting a string into columns using String Interpolation

问题

I need to print doubles so that definite number of symbols (like 8) is allocated for string representation of value. Next words should start at same index from beginning of string in each string. Now I have:

value: 0 test
value: 0.3333333333333 test
value: 0.5 test

I need:

value: 0           test
value: 0.33333333  test
value: 0.5         test

Test code:

double[] ar = new double[] { 0, (double)1 / 3, (double)1 / 2 };
string s = "test";

foreach (var d in ar)
{
    Console.WriteLine($"value: {d} {s}");
}

What should I add after {d:?

回答1:

You can use Alignment Component for this purpose. Like this:

Console.WriteLine($"value: {d,-17} {s}");

The optional alignment component is a signed integer indicating the preferred formatted field width. If the value of alignment is less than the length of the formatted string, alignment is ignored and the length of the formatted string is used as the field width. The formatted data in the field is right-aligned if alignment is positive and left-aligned if alignment is negative. If padding is necessary, white space is used. The comma is required if alignment is specified.

So this is why we use negative alignment because you want the first column be left-aligned.

来源：https://stackoverflow.com/questions/44427194/formatting-a-string-into-columns-using-string-interpolation