GetByteCount Method (Char*, Int32)

Encoding.GetByteCount Method (Char*, Int32)


When overridden in a derived class, calculates the number of bytes produced by encoding a set of characters starting at the specified character pointer.

Namespace:   System.Text
Assembly:  mscorlib (in mscorlib.dll)

public virtual unsafe int GetByteCount(
	char* chars,
	int count


Type: System.Char*

A pointer to the first character to encode.

Type: System.Int32

The number of characters to encode.

Return Value

Type: System.Int32

The number of bytes produced by encoding the specified characters.

Exception Condition

chars is null.


count is less than zero.


A fallback occurred (see Character Encoding in the .NET Framework for complete explanation)


EncoderFallback is set to EncoderExceptionFallback.

To calculate the exact array size that GetBytes requires to store the resulting bytes, you should call the GetByteCount method. To calculate the maximum array size, call the GetMaxByteCount method. The GetByteCount method generally allows allocation of less memory, while the GetMaxByteCount method generally executes faster.

The GetByteCount(Char*, Int32) method determines how many bytes result in encoding a set of Unicode characters, and the GetBytes(Char*, Int32, Byte*, Int32) method performs the actual encoding. The GetBytes method expects discrete conversions, in contrast to the Encoder.GetBytes method, which handles multiple conversions on a single input stream.

Several versions of GetByteCount and GetBytes are supported. The following are some considerations for using these methods:

  • Your app may need to encode many input characters to a code page and process the characters using multiple calls. In this case, you probably need to maintain state between calls, taking into account the state that is persisted by the Encoder object being used.

  • If your app handles string inputs, you should use the string version of the GetBytes method.

  • The Unicode character buffer version of GetBytes allows some fast techniques, particularly with multiple calls using the Encoder object or inserting into existing buffers. Bear in mind, however, that this method version is sometimes unsafe, since pointers are required.

  • If your app must convert a large amount of data, it should reuse the output buffer. In this case, the GetBytes version that supports byte arrays is the best choice.

  • Consider using the Encoder.Convert method instead of GetByteCount. The conversion method converts as much data as possible, and does throw an exception if the output buffer is too small. For continuous encoding of a stream, this method is often the best choice.


Requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
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