将字符串格式化为3位数字

与其这样做，我想利用 string.format()来实现同样的结果:

if (myString.Length < 3)
{
myString =  "00" + 3;
}

179616 次浏览

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It's called Padding:

myString.PadLeft(3, '0')

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最佳答案

If you're just formatting a number, you can just provide the proper custom numeric format to make it a 3 digit string directly:

myString = 3.ToString("000");

Or, alternatively, use the standard D format string:

myString = 3.ToString("D3");

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"How to: Pad a Number with Leading Zeros" http://msdn.microsoft.com/en-us/library/dd260048.aspx

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Does it have to be String.Format?

This looks like a job for String.Padleft

myString=myString.PadLeft(3, '0');

Or, if you are converting direct from an int:

myInt.toString("D3");

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 string.Format("{0:000}", myString);

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You can also do : string.Format("{0:D3}, 3);

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(Can't comment yet with enough reputation , let me add a sidenote)

Just in case your output need to be fixed length of 3-digit , i.e. for number run up to 1000 or more (reserved fixed length), don't forget to add mod 1000 on it .

yourNumber=1001;
yourString= yourNumber.ToString("D3");        // "1001"
yourString= (yourNumber%1000).ToString("D3"); // "001" truncated to 3-digit as expected

Trail sample on Fiddler https://dotnetfiddle.net/qLrePt

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This is how it's done using string interpolation C# 7

$"{myString:000}"

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This is a short hand string format Interpolation:

$"{value:D3}"