[英]c# fixed length string
我需要生成一个固定长度的文本行:
我现在拥有的是:
StringBuilder _sb = new StringBuilder();
_sb.Append(string.Format("{0,5}", "MM")); // serie to cancel
_sb.Append(string.Format("{0,20}", "45444")); // folio to cancel
_sb.Append(string.Format("{0,30}", "AC1122")); // account number (optional)
这很有效,因为生成了 55 个字符的固定长度字符串。
例如,当可选值是一个空字符串时,就会出现问题,例如:
StringBuilder _sb = new StringBuilder();
_sb.Append(string.Format("{0,5}", "MM")); // serie to cancel
_sb.Append(string.Format("{0,20}", "45444")); // folio to cancel
_sb.Append(string.Format("{0,30}", "")); // account number (optional)
在 string.format 中有空字符串则不会给出固定长度,我仍然需要有 30 个字符的长度。
任何线索都非常感谢!
谢谢
您可以使用PadLeft
方法:
StringBuilder _sb = new StringBuilder();
_sb.Append("MM".PadLeft(5)); // serie to cancel
_sb.Append("45444".PadLeft(20)); // folio to cancel
_sb.Append("".PadLeft(30)); // account number (optional)
你确定? 尝试添加一个分隔符,只是为了看看子字符串在哪里结束
StringBuilder _sb = new StringBuilder();
_sb.Append(string.Format("{0,5}|", "MM")); // serie to cancel
_sb.Append(string.Format("{0,20}|", "45444")); // folio to cancel
_sb.Append(string.Format("{0,30}|", "")); // account number (optional
Console.WriteLine(">" + _sb.ToString() + "<");
> MM| 45444| |<
默认情况下,它将添加空字符,直到匹配所需的长度。
示例: "Hello".ToFixedString(10)
将产生"Hello "
。
public static class StringExtensions
{
/// <summary>
/// Extends the <code>String</code> class with this <code>ToFixedString</code> method.
/// </summary>
/// <param name="value"></param>
/// <param name="length">The prefered fixed string size</param>
/// <param name="appendChar">The <code>char</code> to append</param>
/// <returns></returns>
public static String ToFixedString(this String value, int length, char appendChar = ' ')
{
int currlen = value.Length;
int needed = length == currlen ? 0 : (length - currlen);
return needed == 0 ? value :
(needed > 0 ? value + new string(' ', needed) :
new string(new string(value.ToCharArray().Reverse().ToArray()).
Substring(needed * -1, value.Length - (needed * -1)).ToCharArray().Reverse().ToArray()));
}
}
不确定什么是最好的方法,但以下应该有效:
string appended = string.Format("{0,5}", "MM");
appended += string.Format("{0,20}", "45444");
appended += string.Format("{0,30}", "");
public static String FixedStr(this string s, int length, char padChar = ' ')
=> String.IsNullOrEmpty(s) ? new string(padChar, length) : s.Length > length ? s.Remove(length) : s.Length < length ? s.PadRight(length) : s;
示例:
"1234567890".FixedStr(5) = "12345"
"12345".FixedStr(5) = "12345"
"12".FixedStr(5) = "12 "
"".FixedStr(5) = " "
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