Add zero-padding to a string

Question

How do I add "0" padding to a string so that my string length is always 4?

Example

If input "1", 3 padding is added = 0001
If input "25", 2 padding is added = 0025
If input "301", 1 padding is added = 0301
If input "4501", 0 padding is added = 4501

Lightproof

Answer 1

You can use PadLeft

var newString = Your_String.PadLeft(4, '0');

Natalia

Keep in mind that "12345".PadLeft(4,'0') is still "12345" - it won't truncate it. This doesn't detract from this answer by the way since it meets all the specs (there's something strangely satisfying about having an answer you upvoted chosen as the accepted one (though not as satisfying as having one of your own accepted of course), sort of like your son getting into the best school), just thought I'd mention it in case it reared its ugly head sometime in the future. Cripes, I hope those parentheses are balanced :-) – Kinematograph

@paxdiablo: They were until the smiley. – Gothic

"1.2".PadRight(4,'0') also works for zero filling a string number such as "1.20". I can do this to truncate and fill a simple string number < 10000. num = num.length > 4 ? num.Substring(0,4) : num.PadRight(4,'0'); – Passport

Answer 2

myInt.ToString("D4");

Abrasive

The question is how to add padding "to a string." – Experimentalize

string.Format("{0:D4}", myInt) – Nephelometer

Answer 3

string strvalue="11".PadRight(4, '0');

output= 1100

string strvalue="301".PadRight(4, '0');

output= 3010

string strvalue="11".PadLeft(4, '0');

output= 0011

string strvalue="301".PadLeft(4, '0');

output= 0301

Oleoresin

Answer 4

"1".PadLeft(4, '0');

Experimentalize

Answer 5

int num = 1;
num.ToString("0000");

Chlodwig

Answer 6

with sed

• always add three leading zeroes
• then trim to 4 digits

sed -e 's/^/000/;s/^0*\([0-9]\{4,\}\)$/\1/'

Saxtuba