在VB6中实现String.Format（）
可以在VB6中实现String.Format() ，至less是一个足够好的版本，可以在编程好的VB6中使用。
关于VB6string操作性能问题的好资源： http ： //www.aivosto.com/vbtips/stringopt2.html
在相关不，我也想出了一对夫妇string比较函数， 在CodeReview.SE这里find它们
这些function对于提高VB6的可读性非常有用，尤其是如果你最近一直被.net代码所宠坏，突然需要跳入VB6的代码库…享受！
我找不到任何地方，所以我做了我自己的：
Public PADDING_CHAR As String Public Function StringFormat(format_string As String, ParamArray values()) As String 'VB6 implementation of .net String.Format(), slightly customized. 'Tested with Office 2010 VBA (x64) Dim return_value As String Dim values_count As Integer 'some error-handling constants: Const ERR_FORMAT_EXCEPTION As Long = vbObjectError Or 9001 Const ERR_ARGUMENT_NULL_EXCEPTION As Long = vbObjectError Or 9002 Const ERR_SOURCE As String = "StringFormat" Const ERR_MSG_INVALID_FORMAT_STRING As String = "Invalid format string." Const ERR_MSG_FORMAT_EXCEPTION As String = "The number indicating an argument to format is less than zero, or greater than or equal to the length of the args array." 'use SPACE as default padding character If PADDING_CHAR = vbNullString Then PADDING_CHAR = Chr$(32) 'figure out number of passed values: values_count = UBound(values) + 1 Dim regex As RegExp Dim matches As MatchCollection Dim thisMatch As Match Dim thisString As String Dim thisFormat As String 'when format_string starts with "@", escapes are not replaced '(string is treated as a literal string with placeholders) Dim useLiteral As Boolean Dim escapeHex As Boolean 'indicates whether HEX specifier "0x" is to be escaped or not 'validate string_format: Set regex = New RegExp regex.Pattern = "{({{)*(\w+)(,-?\d+)?(:[^}]+)?}(}})*" regex.IgnoreCase = True regex.Global = True Set matches = regex.Execute(format_string) 'determine if values_count matches number of unique regex matches: Dim uniqueCount As Integer Dim tmpCSV As String For Each thisMatch In matches If Not StringContains(tmpCSV, thisMatch.SubMatches(1)) Then uniqueCount = uniqueCount + 1 tmpCSV = tmpCSV & thisMatch.SubMatches(1) & "," End If Next 'unique indices count must match values_count: If matches.Count > 0 And uniqueCount <> values_count Then _ Err.Raise ERR_FORMAT_EXCEPTION, _ ERR_SOURCE, ERR_MSG_FORMAT_EXCEPTION useLiteral = StringStartsWith("@", format_string) 'remove the "@" literal specifier If useLiteral Then format_string = Right(format_string, Len(format_string) - 1) If Not useLiteral And StringContains(format_string, "\\") Then _ format_string = Replace(format_string, "\\", Chr$(27)) If StringContains(format_string, "\\") Then _ format_string = Replace(format_string, "\\", Chr$(27)) If matches.Count = 0 And format_string <> vbNullString And UBound(values) = -1 Then 'only format_string was specified: skip to checking escape sequences: return_value = format_string GoTo checkEscapes ElseIf UBound(values) = -1 And matches.Count > 0 Then Err.Raise ERR_ARGUMENT_NULL_EXCEPTION, _ ERR_SOURCE, ERR_MSG_FORMAT_EXCEPTION End If return_value = format_string 'dissect format_string: Dim i As Integer, v As String, p As String 'i: iterator; v: value; p: placeholder Dim alignmentGroup As String, alignmentSpecifier As String Dim formattedValue As String, alignmentPadding As Integer 'iterate regex matches (each match is a placeholder): For i = 0 To matches.Count - 1 'get the placeholder specified index: Set thisMatch = matches(i) p = thisMatch.SubMatches(1) 'if specified index (0-based) > uniqueCount (1-based), something's wrong: If p > uniqueCount - 1 Then _ Err.Raise ERR_FORMAT_EXCEPTION, _ ERR_SOURCE, ERR_MSG_FORMAT_EXCEPTION v = values(p) 'get the alignment specifier if it is specified: alignmentGroup = thisMatch.SubMatches(2) If alignmentGroup <> vbNullString Then _ alignmentSpecifier = Right$(alignmentGroup, LenB(alignmentGroup) / 2 - 1) 'get the format specifier if it is specified: thisString = thisMatch.Value If StringContains(thisString, ":") Then Dim formatGroup As String, precisionSpecifier As Integer Dim formatSpecifier As String, precisionString As String 'get the string between ":" and "}": formatGroup = Mid$(thisString, InStr(1, thisString, ":") + 1, (LenB(thisString) / 2) - 2) formatGroup = Left$(formatGroup, LenB(formatGroup) / 2 - 1) precisionString = Right$(formatGroup, LenB(formatGroup) / 2 - 1) formatSpecifier = Mid$(thisString, InStr(1, thisString, ":") + 1, 1) 'applicable formatting depends on the type of the value (yes, GOTO!!): If TypeName(values(p)) = "Date" Then GoTo DateTimeFormatSpecifiers If v = vbNullString Then GoTo ApplyStringFormat NumberFormatSpecifiers: If precisionString <> vbNullString And Not IsNumeric(precisionString) Then _ Err.Raise ERR_FORMAT_EXCEPTION, _ ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING If precisionString = vbNullString Then precisionString = 0 Select Case formatSpecifier Case "C", "c" 'CURRENCY format, formats string as currency. 'Precision specifier determines number of decimal digits. 'This implementation ignores regional settings '(hard-coded group separator, decimal separator and currency sign). precisionSpecifier = CInt(precisionString) thisFormat = "#,##0.$" If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then 'if a non-zero precision is specified... thisFormat = _ Replace$(thisFormat, ".", "." & String$(precisionString, Chr$(48))) End If Case "D", "d" 'DECIMAL format, formats string as integer number. 'Precision specifier determines number of digits in returned string. precisionSpecifier = CInt(precisionString) thisFormat = "0" thisFormat = Right$(String$(precisionSpecifier, "0") & thisFormat, _ IIf(precisionSpecifier = 0, Len(thisFormat), precisionSpecifier)) Case "E", "e" 'EXPONENTIAL NOTATION format (aka "Scientific Notation") 'Precision specifier determines number of decimals in returned string. 'This implementation ignores regional settings' '(hard-coded decimal separator). precisionSpecifier = CInt(precisionString) thisFormat = "0.00000#" & formatSpecifier & "-#" 'defaults to 6 decimals If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then 'if a non-zero precision is specified... thisFormat = "0." & String$(precisionSpecifier - 1, Chr$(48)) & "#" & formatSpecifier & "-#" ElseIf LenB(formatGroup) > 2 And precisionSpecifier = 0 Then Err.Raise ERR_FORMAT_EXCEPTION, _ ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING End If Case "F", "f" 'FIXED-POINT format 'Precision specifier determines number of decimals in returned string. 'This implementation ignores regional settings' '(hard-coded decimal separator). precisionSpecifier = CInt(precisionString) thisFormat = "0" If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then 'if a non-zero precision is specified... thisFormat = (thisFormat & ".") & String$(precisionSpecifier, Chr$(48)) Else 'no precision specified - default to 2 decimals: thisFormat = "0.00" End If Case "G", "g" 'GENERAL format (recursive) 'returns the shortest of either FIXED-POINT or SCIENTIFIC formats in case of a Double. 'returns DECIMAL format in case of a Integer or Long. Dim eNotation As String, ePower As Integer, specifier As String precisionSpecifier = IIf(CInt(precisionString) > 0, CInt(precisionString), _ IIf(StringContains(v, "."), Len(v) - InStr(1, v, "."), 0)) 'track character case of formatSpecifier: specifier = IIf(formatSpecifier = "G", "D", "d") If TypeName(values(p)) = "Integer" Or TypeName(values(p)) = "Long" Then 'Integer types: use {0:D} (recursive call): formattedValue = StringFormat("{0:" & specifier & "}", values(p)) ElseIf TypeName(values(p)) = "Double" Then 'Non-integer types: use {0:E} specifier = IIf(formatSpecifier = "G", "E", "e") 'evaluate the exponential notation value (recursive call): eNotation = StringFormat("{0:" & specifier & "}", v) 'get the power of eNotation: ePower = Mid$(eNotation, InStr(1, UCase$(eNotation), "E-") + 1, Len(eNotation) - InStr(1, UCase$(eNotation), "E-")) If ePower > -5 And Abs(ePower) < precisionSpecifier Then 'use {0:F} when ePower > -5 and abs(ePower) < precisionSpecifier: 'evaluate the floating-point value (recursive call): specifier = IIf(formatSpecifier = "G", "F", "f") formattedValue = StringFormat("{0:" & formatSpecifier & _ IIf(precisionSpecifier <> 0, precisionString, vbNullString) & "}", values(p)) Else 'fallback to {0:E} if previous rule didn't apply: formattedValue = eNotation End If End If GoTo AlignFormattedValue 'Skip the "ApplyStringFormat" step, it's applied already. Case "N", "n" 'NUMERIC format, formats string as an integer or decimal number. 'Precision specifier determines number of decimal digits. 'This implementation ignores regional settings' '(hard-coded group and decimal separators). precisionSpecifier = CInt(precisionString) If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then 'if a non-zero precision is specified... thisFormat = "#,##0" thisFormat = (thisFormat & ".") & String$(precisionSpecifier, Chr$(48)) Else 'only the "D" is specified thisFormat = "#,##0" End If Case "P", "p" 'PERCENT format. Formats string as a percentage. 'Value is multiplied by 100 and displayed with a percent symbol. 'Precision specifier determines number of decimal digits. thisFormat = "#,##0%" precisionSpecifier = CInt(precisionString) If LenB(formatGroup) > 2 And precisionSpecifier > 0 Then 'if a non-zero precision is specified... thisFormat = "#,##0" thisFormat = (thisFormat & ".") & String$(precisionSpecifier, Chr$(48)) Else 'only the "P" is specified thisFormat = "#,##0" End If 'Append the percentage sign to the format string: thisFormat = thisFormat & "%" Case "R", "r" 'ROUND-TRIP format (a string that can round-trip to an identical number) 'example: ?StringFormat("{0:R}", 0.0000000001141596325677345362656) ' ...returns "0.000000000114159632567735" 'convert value to a Double (chop off overflow digits): v = CDbl(v) Case "X", "x" 'HEX format. Formats a string as a Hexadecimal value. 'Precision specifier determines number of total digits. 'Returned string is prefixed with "&H" to specify Hex. v = Hex(v) precisionSpecifier = CInt(precisionString) If LenB(precisionString) > 0 Then 'precision here stands for left padding v = Right$(String$(precisionSpecifier, "0") & v, IIf(precisionSpecifier = 0, Len(v), precisionSpecifier)) End If 'add C# hex specifier, apply specified casing: '(VB6 hex specifier would cause Format() to reverse the formatting): v = "0x" & IIf(formatSpecifier = "X", UCase$(v), LCase$(v)) Case Else If IsNumeric(formatSpecifier) And val(formatGroup) = 0 Then formatSpecifier = formatGroup v = Format(v, formatGroup) Else Err.Raise ERR_FORMAT_EXCEPTION, _ ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING End If End Select GoTo ApplyStringFormat DateTimeFormatSpecifiers: Select Case formatSpecifier Case "c", "C" 'CUSTOM date/time format 'let VB Format() parse precision specifier as is: thisFormat = precisionString Case "d" 'SHORT DATE format thisFormat = "ddddd" Case "D" 'LONG DATE format thisFormat = "dddddd" Case "f" 'FULL DATE format (short) thisFormat = "dddddd h:mm AM/PM" Case "F" 'FULL DATE format (long) thisFormat = "dddddd ttttt" Case "g" thisFormat = "ddddd hh:mm AM/PM" Case "G" thisFormat = "ddddd ttttt" Case "s" 'SORTABLE DATETIME format thisFormat = "yyyy-mm-ddThh:mm:ss" Case "t" 'SHORT TIME format thisFormat = "hh:mm AM/PM" Case "T" 'LONG TIME format thisFormat = "ttttt" Case Else Err.Raise ERR_FORMAT_EXCEPTION, _ ERR_SOURCE, ERR_MSG_INVALID_FORMAT_STRING End Select GoTo ApplyStringFormat End If ApplyStringFormat: 'apply computed format string: formattedValue = Format(v, thisFormat) AlignFormattedValue: 'apply specified alignment specifier: If alignmentSpecifier <> vbNullString Then alignmentPadding = Abs(CInt(alignmentSpecifier)) If CInt(alignmentSpecifier) < 0 Then 'negative: left-justified alignment If alignmentPadding - Len(formattedValue) > 0 Then _ formattedValue = formattedValue & _ String$(alignmentPadding - Len(formattedValue), PADDING_CHAR) Else 'positive: right-justified alignment If alignmentPadding - Len(formattedValue) > 0 Then _ formattedValue = String$(alignmentPadding - Len(formattedValue), PADDING_CHAR) & formattedValue End If End If 'Replace C# hex specifier with VB6 hex specifier, 'only if hex specifier was introduced in this function: If (Not useLiteral And escapeHex) And _ StringContains(formattedValue, "0x") Then _ formattedValue = Replace$(formattedValue, "0x", "&H") 'replace all occurrences of placeholder {i} with their formatted values: return_value = Replace(return_value, thisString, formattedValue, Count:=1) 'reset before reiterating: thisFormat = vbNullString Next checkEscapes: 'if there's no more backslashes, don't bother checking for the rest: If useLiteral Or Not StringContains(return_value, "\") Then GoTo normalExit Dim escape As New EscapeSequence Dim escapes As New Collection escapes.Add escape.Create("\n", vbNewLine), "0" escapes.Add escape.Create("\q", Chr$(34)), "1" escapes.Add escape.Create("\t", vbTab), "2" escapes.Add escape.Create("\a", Chr$(7)), "3" escapes.Add escape.Create("\b", Chr$(8)), "4" escapes.Add escape.Create("\v", Chr$(13)), "5" escapes.Add escape.Create("\f", Chr$(14)), "6" escapes.Add escape.Create("\r", Chr$(15)), "7" For i = 0 To escapes.Count - 1 Set escape = escapes(CStr(i)) If StringContains(return_value, escape.EscapeString) Then _ return_value = Replace(return_value, escape.EscapeString, escape.ReplacementString) If Not StringContains(return_value, "\") Then _ GoTo normalExit Next 'replace "ASCII (oct)" escape sequence Set regex = New RegExp regex.Pattern = "\\(\d{3})" regex.IgnoreCase = True regex.Global = True Set matches = regex.Execute(format_string) Dim char As Long If matches.Count <> 0 Then For Each thisMatch In matches p = thisMatch.SubMatches(0) '"p" contains the octal number representing the ASCII code we're after: p = "&O" & p 'prepend octal prefix char = CLng(p) return_value = Replace(return_value, thisMatch.Value, Chr$(char)) Next End If 'if there's no more backslashes, don't bother checking for the rest: If Not StringContains("\", return_value) Then GoTo normalExit 'replace "ASCII (hex)" escape sequence Set regex = New RegExp regex.Pattern = "\\x(\w{2})" regex.IgnoreCase = True regex.Global = True Set matches = regex.Execute(format_string) If matches.Count <> 0 Then For Each thisMatch In matches p = thisMatch.SubMatches(0) '"p" contains the hex value representing the ASCII code we're after: p = "&H" & p 'prepend hex prefix char = CLng(p) return_value = Replace(return_value, thisMatch.Value, Chr$(char)) Next End If normalExit: Set escapes = Nothing Set escape = Nothing If Not useLiteral And StringContains(return_value, Chr$(27)) Then _ return_value = Replace(return_value, Chr$(27), "\") StringFormat = return_value End Function
注意方法签名中的ParamArray （谢谢@wqw）：这样做可以避免使用多个可选参数（以及在调用语句中为参数命名时，可以分配value2而不指定value1情况下使用错误）。 因为它是一个ParamArray ，所以各个值是Variant ，这意味着每个参数都可以是不同的types，VB在幕后进行string转换。
该函数可以像这样消耗：
?StringFormat("(C) Currency: . . . . . . . . {0:C}\n" & _ "(D) Decimal:. . . . . . . . . {0:D}\n" & _ "(E) Scientific: . . . . . . . {1:E}\n" & _ "(F) Fixed point:. . . . . . . {1:F}\n" & _ "(N) Number: . . . . . . . . . {0:N}\n" & _ "(P) Percent:. . . . . . . . . {1:P}\n" & _ "(R) Round-trip: . . . . . . . {1:R}\n" & _ "(X) Hexadecimal:. . . . . . . {0:X}\n",-123, -123.45)
输出：
(C) Currency: . . . . . . . . -123.00$ (D) Decimal:. . . . . . . . . -123 (E) Scientific: . . . . . . . -1.23450E2 (F) Fixed point:. . . . . . . -123 (N) Number: . . . . . . . . . -123 (P) Percent:. . . . . . . . . -12,345% (R) Round-trip: . . . . . . . -123.45 (X) Hexadecimal:. . . . . . . &HFFFFFF85
也是这样的：
?StringFormat("(c) Custom format: . . . . . .{0:cYYYY-MM-DD (MMMM)}\n" & _ "(d) Short date: . . . . . . . {0:d}\n" & _ "(D) Long date:. . . . . . . . {0:D}\n" & _ "(T) Long time:. . . . . . . . {0:T}\n" & _ "(f) Full date/short time: . . {0:f}\n" & _ "(F) Full date/long time:. . . {0:F}\n" & _ "(s) Sortable: . . . . . . . . {0:s}\n", Now())
输出：
(c) Custom format: . . . . . .2013-01-26 (January) (d) Short date: . . . . . . . 1/26/2013 (D) Long date:. . . . . . . . Saturday, January 26, 2013 (T) Long time:. . . . . . . . 8:28:11 PM (f) Full date/short time: . . 1/26/2013 8:28:11 PM (F) Full date/long time:. . . Saturday, January 26, 2013 8:28:11 PM (s) Sortable: . . . . . . . . 2013-01-26T20:28:11
还可以指定alignment方式（/填充）并使用转义序列：
?StringFormat ("\q{0}, {1}!\x20\n'{2,10:C2}'\n'{2,-10:C2}'", "hello", "world", 100) "hello, world!" ' 100.00$' '100.00$ '
查看http://msdn.microsoft.com/fr-fr/library/b1csw23d(v=vs.80).aspx中的示例，只有几个格式说明符未实现，主要是date/时间说明符…但是，会认为“C”自定义date/时间格式说明符弥补。
该函数使用String.Contains()一个简单的实现：
Public Function StringContains(string_source As String, find_text As String, _ Optional ByVal caseSensitive As Boolean = True) As Boolean StringContains = StringContainsAny(string_source, caseSensitive, find_text) End Function
编辑：此代码现在正确处理“\\”转义，如注释中所述。 另外，虽然StringContains当然是实用的，并且比InStr()调用给出更舒适的阅读，但下面的StringContainsAny函数甚至更好：
Public Function StringContainsAny(string_source As String, ByVal caseSensitive As Boolean, _ ParamArray find_values()) As Boolean Dim i As Integer, found As Boolean If caseSensitive Then For i = LBound(find_values) To UBound(find_values) found = (InStr(1, string_source, _ find_values(i), vbBinaryCompare) <> 0) If found Then Exit For Next Else For i = LBound(find_values) To UBound(find_values) StringContainsAny = (InStr(1, LCase$(string_source), _ LCase$(find_values(i)), vbBinaryCompare) <> 0) If found Then Exit For Next End If StringContainsAny = found End Function
考虑以下：
foo = Instr(1, source, "value1") > 0 Or Instr(1, source, "value2") > 0 _ Or Instr(1, source, "value3") > 0 Or Instr(1, source, "value4") > 0 _ Or Instr(1, source, "value5") > 0 Or Instr(1, source, "value6") > 0 _
在VB可以确定foo是TRUE还是FALSE ，每个InStr()调用都会被调用。 但是对于StringContainsAny() ，条件满足于find的第一个值，这使得它更快。
编辑：以前的编辑几乎消灭了转义序列; 恢复他们，使用一个小的类“EscapeSequence”暴露两个属性和一个工厂方法 – 这样做可以保持for-each循环和处理所有简单的转义，而不会重复太多的代码。
这段代码也使用了一个StringStartsWith函数，像这样实现：
Public Function StringStartsWith(ByVal find_text As String, ByVal string_source As String, Optional ByVal caseSensitive As Boolean = True) As Boolean If caseSensitive Then StringStartsWith = (Left$(string_source, LenB(find_text) / 2) = find_text) Else StringStartsWith = (Left$(LCase(string_source), LenB(find_text) / 2) = LCase$(find_text)) End If End Function
