BinaryReader.ReadDouble Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Reads an 8-byte floating point value from the current stream and advances the current position of the stream by eight bytes.
public:
virtual double ReadDouble();public virtual double ReadDouble ();abstract member ReadDouble : unit -> double
override this.ReadDouble : unit -> doublePublic Overridable Function ReadDouble () As DoubleReturns
An 8-byte floating point value read from the current stream.
Exceptions
The end of the stream is reached.
The stream is closed.
An I/O error occurred.
Examples
The following code example shows how to read and write Double data to memory by using the BinaryReader and BinaryWriter classes on top of the MemoryStream class. MemoryStream only reads and writes Byte data.
using namespace System;
using namespace System::IO;
int main()
{
int i;
const int arrayLength = 1000;
// Create random data to write to the stream.
array<double>^dataArray = gcnew array<double>(arrayLength);
Random^ randomGenerator = gcnew Random;
for ( i = 0; i < arrayLength; i++ )
{
dataArray[ i ] = 100.1 * randomGenerator->NextDouble();
}
BinaryWriter^ binWriter = gcnew BinaryWriter( gcnew MemoryStream );
try
{
// Write data to the stream.
Console::WriteLine( "Writing data to the stream." );
i = 0;
for ( i = 0; i < arrayLength; i++ )
{
binWriter->Write( dataArray[ i ] );
}
// Create a reader using the stream from the writer.
BinaryReader^ binReader = gcnew BinaryReader( binWriter->BaseStream );
// Return to the beginning of the stream.
binReader->BaseStream->Position = 0;
try
{
// Read and verify the data.
i = 0;
Console::WriteLine( "Verifying the written data." );
for ( i = 0; i < arrayLength; i++ )
{
if ( binReader->ReadDouble() != dataArray[ i ] )
{
Console::WriteLine( "Error writing data." );
break;
}
}
Console::WriteLine( "The data was written and verified." );
}
catch ( EndOfStreamException^ e )
{
Console::WriteLine( "Error writing data: {0}.", e->GetType()->Name );
}
}
finally
{
binWriter->Close();
}
}
using System;
using System.IO;
class BinaryRW
{
static void Main()
{
int i;
const int arrayLength = 1000;
// Create random data to write to the stream.
Random randomGenerator = new Random();
double[] dataArray = new double[arrayLength];
for(i = 0; i < arrayLength; i++)
{
dataArray[i] = 100.1 * randomGenerator.NextDouble();
}
using(BinaryWriter binWriter =
new BinaryWriter(new MemoryStream()))
{
// Write the data to the stream.
Console.WriteLine("Writing data to the stream.");
for(i = 0; i < arrayLength; i++)
{
binWriter.Write(dataArray[i]);
}
// Create a reader using the stream from the writer.
using(BinaryReader binReader =
new BinaryReader(binWriter.BaseStream))
{
try
{
// Return to the beginning of the stream.
binReader.BaseStream.Position = 0;
// Read and verify the data.
Console.WriteLine("Verifying the written data.");
for(i = 0; i < arrayLength; i++)
{
if(binReader.ReadDouble() != dataArray[i])
{
Console.WriteLine("Error writing data.");
break;
}
}
Console.WriteLine("The data was written " +
"and verified.");
}
catch(EndOfStreamException e)
{
Console.WriteLine("Error writing data: {0}.",
e.GetType().Name);
}
}
}
}
}
open System
open System.IO
let arrayLength = 1000
// Create random data to write to the stream.
let randomGenerator = Random()
let dataArray =
Array.init arrayLength (fun _ -> 100.1 * randomGenerator.NextDouble())
do
use binWriter = new BinaryWriter(new MemoryStream())
// Write the data to the stream.
printfn $"Writing data to the stream."
for num in dataArray do
binWriter.Write num
// Create a reader using the stream from the writer.
use binReader = new BinaryReader(binWriter.BaseStream)
try
// Return to the beginning of the stream.
binReader.BaseStream.Position <- 0
// Read and verify the data.
printfn "Verifying the written data."
for num in dataArray do
if binReader.ReadDouble() <> num then
printfn "Error writing data."
printfn "The data was written and verified."
with :? EndOfStreamException as e ->
printfn $"Error writing data: {e.GetType().Name}."
Imports System.IO
Public Class BinaryRW
Shared Sub Main()
Dim i As Integer
Const upperBound As Integer = 1000
' Create random data to write to the stream.
Dim dataArray(upperBound) As Double
Dim randomGenerator As New Random()
For i = 0 To upperBound
dataArray(i) = 100.1 * randomGenerator.NextDouble()
Next i
Dim binWriter As New BinaryWriter(New MemoryStream())
Try
' Write data to the stream.
Console.WriteLine("Writing data to the stream.")
For i = 0 To upperBound
binWriter.Write(dataArray(i))
Next i
' Create a reader using the stream from the writer.
Dim binReader As New BinaryReader(binWriter.BaseStream)
' Return to the beginning of the stream.
binReader.BaseStream.Position = 0
' Read and verify the data.
Try
Console.WriteLine("Verifying the written data.")
For i = 0 To upperBound
If binReader.ReadDouble() <> dataArray(i) Then
Console.WriteLine("Error writing data.")
Exit For
End If
Next i
Console.WriteLine("The data was written and verified.")
Catch ex As EndOfStreamException
Console.WriteLine("Error writing data: {0}.", _
ex.GetType().Name)
End Try
Finally
binWriter.Close()
End Try
End Sub
End Class
Remarks
BinaryReader does not restore the file position after an unsuccessful read.
BinaryReader reads this data type in little-endian format.
For a list of common I/O tasks, see Common I/O Tasks.
Applies to
See also
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