Pad the value with leading zero using D format specifier in C#

You can pad an integer with leading zeros by using the “D” string format specifier. You can pad integer, floating-point and negative numbers with leading zeros by using a “D” format string.

The following example formats all four integral types values including negative value to the string of length 8.

byte byteValue = 254;
short shortValue = 10342;
int intValue = 10;
int negativeValue = -254;
 
Console.WriteLine(byteValue.ToString("D6"));
Console.WriteLine(shortValue.ToString("D6"));
Console.WriteLine(intValue.ToString("D6"));
Console.WriteLine(negativeValue.ToString("D6"));
Console.WriteLine();

The result of the above code will be:

000254
010342
000010
-000254

The “D” format specifier converts a number to a string of decimal digits. This format is supported only for integral types.

To pad an integer with a specific number of leading zeros

The following example adds the three leading zeros into the integral types values:

byte byteValue = 254;
short shortValue = 10342;
 
Console.WriteLine(byteValue.ToString("D").Length + 3);
Console.WriteLine(shortValue.ToString("D").Length + 3));
Console.WriteLine();

The result of the above code will be:
000254
00010342