UTF32Encoding.GetCharCount 方法
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
計算將位元組序列解碼所產生的字元數。
多載
| GetCharCount(Byte[], Int32, Int32) |
計算將指定位元組陣列中的位元組序列解碼所產生的字元數。 |
| GetCharCount(Byte*, Int32) |
計算將起始於指定位元組指標的位元組序列解碼所產生的字元數。 |
GetCharCount(Byte[], Int32, Int32)
計算將指定位元組陣列中的位元組序列解碼所產生的字元數。
public:
override int GetCharCount(cli::array <System::Byte> ^ bytes, int index, int count);public override int GetCharCount (byte[] bytes, int index, int count);override this.GetCharCount : byte[] * int * int -> intPublic Overrides Function GetCharCount (bytes As Byte(), index As Integer, count As Integer) As Integer參數
- bytes
- Byte[]
包含要解碼之位元組序列的位元組陣列。
- index
- Int32
要解碼的第一個位元組索引。
- count
- Int32
要解碼的位元組數。
傳回
解碼指定位元組序列所產生的字元數。
例外狀況
bytes 為 null。
index 或 count 小於零。
-或-
index 與 count 不代表 bytes 中有效的範圍。
-或-
所產生的位元組數目大於可用整數傳回的數目上限。
已啟用錯誤偵測，而且 bytes 包含無效的位元組序列。
發生後援 (如需詳細資訊，請參閱 .NET 中的字元編碼)
-和-
範例
下列範例會將字串編碼為位元組陣列，然後將位元組解碼為字元陣列。
using namespace System;
using namespace System::Text;
void PrintCountsAndChars( array<Byte>^bytes, Encoding^ enc );
int main()
{
// Create two instances of UTF32Encoding: one with little-endian byte order and one with big-endian byte order.
UTF32Encoding^ u32LE = gcnew UTF32Encoding( false,true,true );
UTF32Encoding^ u32BE = gcnew UTF32Encoding( true,true,true );
// Create byte arrays from the same string containing the following characters:
// Latin Small Letter Z (U+007A)
// Latin Small Letter A (U+0061)
// Combining Breve (U+0306)
// Latin Small Letter AE With Acute (U+01FD)
// Greek Small Letter Beta (U+03B2)
String^ myStr = L"za\u0306\u01FD\u03B2\xD8FF\xDCFF";
// barrBE uses the big-endian byte order.
array<Byte>^barrBE = gcnew array<Byte>(u32BE->GetByteCount( myStr ));
u32BE->GetBytes( myStr, 0, myStr->Length, barrBE, 0 );
// barrLE uses the little-endian byte order.
array<Byte>^barrLE = gcnew array<Byte>(u32LE->GetByteCount( myStr ));
u32LE->GetBytes( myStr, 0, myStr->Length, barrLE, 0 );
// Get the char counts and decode the byte arrays.
Console::Write( "BE array with BE encoding : " );
PrintCountsAndChars( barrBE, u32BE );
Console::Write( "LE array with LE encoding : " );
PrintCountsAndChars( barrLE, u32LE );
// Decode the byte arrays using an encoding with a different byte order.
Console::Write( "BE array with LE encoding : " );
try
{
PrintCountsAndChars( barrBE, u32LE );
}
catch ( System::ArgumentException^ e )
{
Console::WriteLine( e->Message );
}
Console::Write( "LE array with BE encoding : " );
try
{
PrintCountsAndChars( barrLE, u32BE );
}
catch ( System::ArgumentException^ e )
{
Console::WriteLine( e->Message );
}
}
void PrintCountsAndChars( array<Byte>^bytes, Encoding^ enc )
{
// Display the name of the encoding used.
Console::Write( "{0,-25} :", enc );
// Display the exact character count.
int iCC = enc->GetCharCount( bytes );
Console::Write( " {0,-3}", iCC );
// Display the maximum character count.
int iMCC = enc->GetMaxCharCount( bytes->Length );
Console::Write( " {0,-3} :", iMCC );
// Decode the bytes and display the characters.
array<Char>^chars = gcnew array<Char>(iCC);
enc->GetChars( bytes, 0, bytes->Length, chars, 0 );
Console::WriteLine( chars );
}
/*
This code produces the following output. The question marks take the place of characters that cannot be displayed at the console.
BE array with BE encoding : System.Text.UTF32Encoding : 7 14 :za??�?
LE array with LE encoding : System.Text.UTF32Encoding : 7 14 :za??�?
BE array with LE encoding : System.Text.UTF32Encoding :Invalid byte was found at byte index 3.
LE array with BE encoding : System.Text.UTF32Encoding :Invalid byte was found at byte index 3.
*/
using System;
using System.Text;
public class SamplesUTF32Encoding {
public static void Main() {
// Create two instances of UTF32Encoding: one with little-endian byte order and one with big-endian byte order.
UTF32Encoding u32LE = new UTF32Encoding( false, true, true );
UTF32Encoding u32BE = new UTF32Encoding( true, true, true );
// Create byte arrays from the same string containing the following characters:
// Latin Small Letter Z (U+007A)
// Latin Small Letter A (U+0061)
// Combining Breve (U+0306)
// Latin Small Letter AE With Acute (U+01FD)
// Greek Small Letter Beta (U+03B2)
// a high-surrogate value (U+D8FF)
// a low-surrogate value (U+DCFF)
String myStr = "za\u0306\u01FD\u03B2\uD8FF\uDCFF";
// barrBE uses the big-endian byte order.
byte[] barrBE = new byte[u32BE.GetByteCount( myStr )];
u32BE.GetBytes( myStr, 0, myStr.Length, barrBE, 0 );
// barrLE uses the little-endian byte order.
byte[] barrLE = new byte[u32LE.GetByteCount( myStr )];
u32LE.GetBytes( myStr, 0, myStr.Length, barrLE, 0 );
// Get the char counts and decode the byte arrays.
Console.Write( "BE array with BE encoding : " );
PrintCountsAndChars( barrBE, u32BE );
Console.Write( "LE array with LE encoding : " );
PrintCountsAndChars( barrLE, u32LE );
// Decode the byte arrays using an encoding with a different byte order.
Console.Write( "BE array with LE encoding : " );
try {
PrintCountsAndChars( barrBE, u32LE );
}
catch ( System.ArgumentException e ) {
Console.WriteLine( e.Message );
}
Console.Write( "LE array with BE encoding : " );
try {
PrintCountsAndChars( barrLE, u32BE );
}
catch ( System.ArgumentException e ) {
Console.WriteLine( e.Message );
}
}
public static void PrintCountsAndChars( byte[] bytes, Encoding enc ) {
// Display the name of the encoding used.
Console.Write( "{0,-25} :", enc.ToString() );
// Display the exact character count.
int iCC = enc.GetCharCount( bytes );
Console.Write( " {0,-3}", iCC );
// Display the maximum character count.
int iMCC = enc.GetMaxCharCount( bytes.Length );
Console.Write( " {0,-3} :", iMCC );
// Decode the bytes and display the characters.
char[] chars = new char[iCC];
enc.GetChars( bytes, 0, bytes.Length, chars, 0 );
Console.WriteLine( chars );
}
}
Imports System.Text
Public Class SamplesUTF32Encoding
Public Shared Sub Main()
' Create two instances of UTF32Encoding: one with little-endian byte order and one with big-endian byte order.
Dim u32LE As New UTF32Encoding(False, True, True)
Dim u32BE As New UTF32Encoding(True, True, True)
' Create byte arrays from the same string containing the following characters:
' Latin Small Letter Z (U+007A)
' Latin Small Letter A (U+0061)
' Combining Breve (U+0306)
' Latin Small Letter AE With Acute (U+01FD)
' Greek Small Letter Beta (U+03B2)
' a high-surrogate value (U+D8FF)
' a low-surrogate value (U+DCFF)
Dim myStr As String = "za" & ChrW(&H0306) & ChrW(&H01FD) & ChrW(&H03B2) & ChrW(&HD8FF) & ChrW(&HDCFF)
' barrBE uses the big-endian byte order.
' NOTE: In Visual Basic, arrays contain one extra element by default.
' The following line creates an array with the exact number of elements required.
Dim barrBE(u32BE.GetByteCount(myStr) - 1) As Byte
u32BE.GetBytes(myStr, 0, myStr.Length, barrBE, 0)
' barrLE uses the little-endian byte order.
' NOTE: In Visual Basic, arrays contain one extra element by default.
' The following line creates an array with the exact number of elements required.
Dim barrLE(u32LE.GetByteCount(myStr) - 1) As Byte
u32LE.GetBytes(myStr, 0, myStr.Length, barrLE, 0)
' Get the char counts and decode the byte arrays.
Console.Write("BE array with BE encoding : ")
PrintCountsAndChars(barrBE, u32BE)
Console.Write("LE array with LE encoding : ")
PrintCountsAndChars(barrLE, u32LE)
' Decode the byte arrays using an encoding with a different byte order.
Console.Write("BE array with LE encoding : ")
Try
PrintCountsAndChars(barrBE, u32LE)
Catch e As System.ArgumentException
Console.WriteLine(e.Message)
End Try
Console.Write("LE array with BE encoding : ")
Try
PrintCountsAndChars(barrLE, u32BE)
Catch e As System.ArgumentException
Console.WriteLine(e.Message)
End Try
End Sub
Public Shared Sub PrintCountsAndChars(bytes() As Byte, enc As Encoding)
' Display the name of the encoding used.
Console.Write("{0,-25} :", enc.ToString())
' Display the exact character count.
Dim iCC As Integer = enc.GetCharCount(bytes)
Console.Write(" {0,-3}", iCC)
' Display the maximum character count.
Dim iMCC As Integer = enc.GetMaxCharCount(bytes.Length)
Console.Write(" {0,-3} :", iMCC)
' Decode the bytes and display the characters.
Dim chars(iCC) As Char
enc.GetChars(bytes, 0, bytes.Length, chars, 0)
Console.WriteLine(chars)
End Sub
End Class
備註
方法 GetCharCount 會計算方法儲存所產生字元所需的 GetChars 確切陣列大小。 若要計算陣列大小上限，請呼叫 GetMaxCharCount 方法。 方法 GetCharCount 通常會配置較少的記憶體，而 GetMaxCharCount 方法通常執行速度較快。
使用錯誤偵測時，不正確序列會導致這個方法擲回 ArgumentException 。 如果沒有錯誤偵測，則會忽略不正確序列，而且不會擲回任何例外狀況。
另請參閱
適用於
GetCharCount(Byte*, Int32)
重要
此 API 不符合 CLS 規範。
計算將起始於指定位元組指標的位元組序列解碼所產生的字元數。
public:
override int GetCharCount(System::Byte* bytes, int count);[System.CLSCompliant(false)]
[System.Security.SecurityCritical]
public override int GetCharCount (byte* bytes, int count);[System.CLSCompliant(false)]
public override int GetCharCount (byte* bytes, int count);[<System.CLSCompliant(false)>]
[<System.Security.SecurityCritical>]
override this.GetCharCount : nativeptr<byte> * int -> int[<System.CLSCompliant(false)>]
override this.GetCharCount : nativeptr<byte> * int -> int參數
- bytes
- Byte*
要解碼的第一個位元組指標。
- count
- Int32
要解碼的位元組數。
傳回
解碼指定位元組序列所產生的字元數。
- 屬性
例外狀況
bytes 為 null。
已啟用錯誤偵測，而且 bytes 包含無效的位元組序列。
發生後援 (如需詳細資訊，請參閱 .NET 中的字元編碼)
-和-
備註
GetCharCount 計算方法儲存所產生字元所需的 GetChars 確切陣列大小。 若要計算陣列大小上限，請呼叫 GetMaxCharCount 方法。 方法 GetCharCount 通常會配置較少的記憶體，而 GetMaxCharCount 方法通常執行速度較快。
使用錯誤偵測時，不正確序列會導致這個方法擲回 ArgumentException 。 如果沒有錯誤偵測，則會忽略不正確序列，而且不會擲回任何例外狀況。
另請參閱
適用於
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