字符串自定义格式化程序 .NET

Question

自定义格式字符串有一个问题。
我想做这样的事:

var str = "SOME_ORIGINAL_FIELD_NAME";
var format1 = "XX_X_X";
var format2 = "X_XXX";

var strFormat1 = String.Format(str, format1); // SOMEORIGINAL_FIELD_NAME
var strFormat2 = String.Format(str, format2); // SOME_ORIGINALFIELDNAME

有谁知道正确的搜索方向吗？也许我应该看看 IFormatProvider 和 ICustomFormatter 方面。

Answer 1

将格式字符串中的 X 替换为连续的占位符，并将输入字符串值拆分为字符串数组，然后应用 string.Format():

public static string FormatSplitAndJoin(string input, string formatTemplate, string delimiter = "_", string placeholder = "X")
{
    // split "a_b_c" into ["a", "b", "c"]
    var parts = input.Split(delimiter);

    // turn "X_X_X" into "{0}_{1}_{2}"
    var index = 0;
    var formatString = Regex.Replace(formatTemplate, placeholder, m => string.Format("{{{0}}}", index++));

    // validate input length
    if(index > parts.Length)
        throw new ArgumentException(string.Format("input string resulted in fewer arguments than expected, {0} placeholders found", index));

    // apply string.Format()
    return string.Format(formatString, parts);
}

现在您可以：

var str = "SOME_ORIGINAL_FIELD_NAME";
var format1 = "XX_X_X";
var format2 = "X_XXX";

var strFormat1 = FormatSplitAndJoin(str, format1); // SOMEORIGINAL_FIELD_NAME
var strFormat2 = FormatSplitAndJoin(str, format2); // SOME_ORIGINALFIELDNAME

Answer 2

当然可以，您只需要：

将源字符串拆分为其组件，
使用 {i} 占位符代替 X，并且
将参数反转为String.Format（格式在前，数据在后）。

示例代码 (fiddle):

var components = "SOME_ORIGINAL_FIELD_NAME".Split('_');
var format1 = "{0}{1}_{2}_{3}";
var format2 = "{0}_{1}{2}{3}";

var strFormat1 = String.Format(format1, components); // SOMEORIGINAL_FIELD_NAME
var strFormat2 = String.Format(format2, components); // SOME_ORIGINALFIELDNAME

字符串自定义格式化程序 .NET

String custom formatter .NET

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string

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