SetLength Method

MemoryStream.SetLength Method (Int64)


Sets the length of the current stream to the specified value.

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

public override void SetLength(
	long value


Type: System.Int64

The value at which to set the length.

Exception Condition

The current stream is not resizable and value is larger than the current capacity.


The current stream does not support writing.


value is negative or is greater than the maximum length of the MemoryStream, where the maximum length is(MaxValue - origin), and origin is the index into the underlying buffer at which the stream starts.

This method overrides SetLength.

If the specified value is less than the current length of the stream, the stream is truncated. If after the truncation the current position within the stream is past the end of the stream, the ReadByte method returns -1, the Read method reads zero bytes into the provided byte array, and Write and WriteByte methods append specified bytes at the end of the stream, increasing its length. If the specified value is larger than the current capacity and the stream is resizable, the capacity is increased, and the current position within the stream is unchanged. If the length is increased, the contents of the stream between the old and the new length are initialized to zeros.


A MemoryStream instance must support writing for this method to work. Use the CanWrite property to determine whether the current instance supports writing. For additional information, see CanWrite.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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