如何在c#中将字符串截断或填充为固定长度

Question

Is there a one-liner way of setting a string to a fixed length (in C#), either by truncating it or padding it with spaces ( ' ' ).

For example:

string s1 = "abcdef";
string s2 = "abc";

after setting both to length 5 , we should have:

"abcde"
"abc  "

Answer 1

All you need is PadRight followed by Substring (providing that source is not null ):

string source = ...
int length = 5;

string result = source.PadRight(length).Substring(0, length);

In case source can be null :

string result = source == null 
  ? new string(' ', length) 
  : source.PadRight(length).Substring(0, length);

Answer 2

private string fixedLength(string input, int length){
    if(input.Length > length)
        return input.Substring(0,length);
    else
        return input.PadRight(length, ' ');
}

Answer 3

(This answer previously contained incorrect code, as referenced in the comments.)

A custom one-liner would be str.Length > 5 ? str.Substring(0,5) : str.PadRight(5); str.Length > 5 ? str.Substring(0,5) : str.PadRight(5); .

Answer 4

Have you tried s1.PadLeft(5);

you can also specify the character for padding if you want something else than spaces

s1.PadLeft(6, '.');

Would give you: "abcdef."

to do both:

var s1 = "1234567890";
var s2 = s1.SubString(5).PadLeft(5);

Answer 5

I would use the @waka answer, but as an extension method and null verification, like this:

    public static string FixedLength(this string value, int totalWidth, char paddingChar)
    {
        if (value is null)
            return new string(paddingChar, totalWidth);

        if (value.Length > totalWidth)
            return value.Substring(0, totalWidth);
        else
            return value.PadRight(totalWidth, paddingChar);
    }

Answer 6

你可以使用string.PadLeft或string.PadRight https://msdn.microsoft.com/en-us/library/66f6d830(v=vs.110).aspx