有没有更简单的方法可以在 C# 中格式化具有确切长度的字符串?

Question

我需要将字符串格式化为正好是x个字符，但是我要格式化的值可以是任何长度。

"" => "          "
"New York" => "New York  "
"New York City" => "New York C"

目前，我正在这样做：

$"{(address.City.Substring(0, address.City.Length > 20 ? 20 : address.City.Length)),20}"

Bu 这变得非常乏味且容易出错，我做的越多：

var builder = new StringBuilder();
builder.AppendLine($"{(address.Street1.Substring(0, address.Street1.Length > 30 ? 30 : address.Street1.Length)),30}");
builder.AppendLine($"{(address.Street2.Substring(0, address.Street2.Length > 30 ? 30 : address.Street2.Length)),30}");
builder.AppendLine($"{(address.City.Substring(0, address.City.Length > 20 ? 20 : address.City.Length)),20}");
builder.AppendLine($"{(address.State.Substring(0, address.State.Length > 5 ? 5 : address.State.Length)),5}");
builder.AppendLine($"{(address.Zip.Substring(0, address.Zip.Length > 10 ? 10 : address.Zip.Length)),10}");
var result = builder.ToString();

我还有大约30件其他事情需要做。如果有这样的东西，那就太好了：

address.City.SubstringExact(0, 20)

Answer 1

你可以添加一个扩展方法到字符串，这将为你做到这一点：

public static class StringExtensions
{
public static string ToLength(this string self, int length)
{
if(self == null)
return null;
return self.Length > length ? self.Substring(0, length) : self.PadRight(length);
}
}

Answer 2

尝试str.PadRight(x, ' ').Substring(0, x);

string str1 = "";
string res1 = str1.PadRight(10, ' ').Substring(0, 10);
// "          "
string str2 = "New York  ";
string res2 = str2.PadRight(10, ' ').Substring(0, 10);
//"New York  "
string str3 = "New York C";
string res3 = str3.PadRight(10, ' ').Substring(0, 10);
//"New York C"

Answer 3

您可以使用填充创建扩展方法：

public static class StringExtensions
{
public static string SubstringExact(this string src, int start, int length) 
{
return src.PadRight(start + length).Substring(start, length);
} 
}