將「掩碼」應用於字符串

Question

我有一個標記枚舉（int）掩碼，我需要將其轉換爲表示一週的日期的字符串。

說這是滿弦和任意麪具

strFullWeek = "MTWtFSs" 
strWeekMask = "0100110" 
----------------------- 
strResult = "-T--FS-" 

你會提出從全周和掩碼串獲得strResult什麼辦法嗎？

UPDATE

這是我的 「全方面」（VB.NET）

<Flags()> Public Enum Week 
    Monday = 1 
    Tuesday = 2 
    Wednesday = 4 
    Thursday = 8 
    Friday = 16 
    Saturday = 32 
    Sunday = 64 
End Enum 

Dim mondayOrSunday = Week.Monday Or Week.Sunday 
Dim strDays = "MTWtFSs" 

Dim strMondayOrSundayBinary = Convert.ToString(
    mondayOrSunday, 2).PadRight(7, CChar("0")) 

Dim charMondayOrSunday = strDays.Zip(
    strMondayOrSundayBinary, 
    Function(day, mask) If(mask = CChar("1"), day, CChar("-"))).ToArray() 

Dim strMondayOrSunday = New String(charMondayOrSunday) 

Console.WriteLine("{0} I see as {1}", 
        mondayOrSunday, 
        strMondayOrSunday) 

Answer 1

有一個合理的整潔LINQ方式：

var chars = strFullWeek.Zip(strWeekMask, (day, mask) => mask == '1' ? day : '-')) 
         .ToArray(); 
string text = new string(chars); 

它不會是非常有效的，但它可能已經足夠好了......

編輯：好吧，假設你很滿意C＃代碼的enum版本離子

// TODO: Rename "Week" to comply with .NET naming conventions 
Week mask = Week.Monday | Week.Sunday; 
var chars = strFullWeek.Select((value, index) => (int) mask & (1 << index) != 0) 
               ? value : '-') 
         .ToArray(); 
string text = new string(chars); 

Answer 2

在這裏你去：

var strFullWeek = "MTWtFSs"; 
var strWeekMask = "0100110"; 

var strFullWeekArray = strFullWeek.ToList(); 
var strWeekMaskArray = strWeekMask.ToList(); 

Console.WriteLine(string.Join(
    string.Empty, 
    strFullWeek.Select(c => (strWeekMaskArray[strFullWeekArray.IndexOf(c)] == '1') 
     ? c 
     : '-'))); 

Answer 3

下面是一個選擇，如果你正在尋找可讀性：

string fullWeek = "MTWtFSs"; 
string weekMask = "0100110"; 

const char blankChar = '-'; 

int totalChars = fullWeek.Length; 

StringBuilder result = new StringBuilder(); 

for (int index = 0; index < totalChars; index++) 
{ 
    if (weekMask[index] == '1') 
    { 
     result.Append(fullWeek[index]); 
    } 
    else 
    { 
     result.Append(blankChar); 
    } 
} 

Console.WriteLine(result); 

Answer 4

我迅速的解決方案使用StringBuilder。它允許你就地操作字符串。但是，除非您將此代碼調用一百萬次，否則與LINQ解決方案相比，您不會注意到速度上的任何差異。

string strFullWeek = "MTWtFSs"; 
string strWeekMask = "0100110"; 

var sb = new StringBuilder(strFullWeek); 
for (int i = 0; i < strWeekMask.Length; i++) { 
    if (strWeekMask[i] == '0') { 
     sb[i] = '-'; 
    } 
} 
string result = sb.ToString(); 

Answer 5

我遲到了;但我想嘗試。這是我不太爽LINQ方法：

var result = new string(strFullWeek.Select((letter, index) 
         => strWeekMask[index] == '1' ? letter : '-').ToArray()); 

Answer 6

如果您想直接使用枚舉，你可以像這樣的東西這樣做：

[Flags()] 
enum Week 
{ 
    Monday = 1, 
    Tuesday = 2, 
    Wednesday = 4, 
    Thursday = 8, 
    Friday = 16, 
    Saturday = 32, 
    Sunday = 64 
} 

const string strFullWeek = "MTWtFSs"; 

string GetMaskedWeek(Week days) 
{ 
    char[] result = new char[strFullWeek.Length]; 
    for (int i = 0; i < strFullWeek.Length; i++) 
    { 
     if ((((int)days >> i) & 1) != 0) 
      result[i] = strFullWeek.ToCharArray(i, 1)[0]; 
     else 
      result[i] = '-'; 
    } 
    return new string(result); 
} 

或者，在VB.NET：

<Flags()> Public Enum Week 
    Monday = 1 
    Tuesday = 2 
    Wednesday = 4 
    Thursday = 8 
    Friday = 16 
    Saturday = 32 
    Sunday = 64 
End Enum 

Dim strFullWeek As String = "MTWtFSs" 

Private Function GetMaskedWeek(ByVal days As Week) As String 
    Dim result(strFullWeek.Length) As Char 
    For i As Integer = 0 To strFullWeek.Length - 1 
     If ((days >> i) And 1) <> 0 Then 
      result(i) = strFullWeek.ToCharArray(i, 1)(0) 
     Else 
      result(i) = "-"c 
     End If 
    Next 
    Return New String(result) 
End Function