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==BinaryReader==

C# defines two binary stream classes that can be used to read and write binary data directly.
<OL><LI>BinaryReader.</LI><LI>BinaryWriter.</LI></OL>
A BinaryReader is a wrapper around a byte stream that handles the reading of binary data.
Method
Description
int Read()
Returns an integer representation of the next available character. Returns -1 when the end of the file is encountered.
int Read(byte[ ] buf, int offset, int num)
Attempts to read up to num bytes into buf starting at buf[offset], returning the number of bytes successfully read.
int Read(char[ ] buf, int offset, int num)
Attempts to read up to num characters into buf starting at buf[offset], returning the number of characters successfully read.
Commonly Used Input Methods Defined by BinaryReader
Method
Description
bool ReadBoolean()
Reads a bool.
byte ReadByte()
Reads a byte.
sbyte ReadSByte()
Reads an sbyte
byte[] ReadBytes(int num)
Reads num bytes and returns them as an array.
char ReadChar()
Reads a char.
char[] ReadChar(int num)
Reads num characteds and returns them as an array
double ReadDouble()
Reads a double
float ReadSingle()
Reads a float
short ReadInt16()
Reads a short
int ReadInt32()
Reads an int
long ReadInt64()
Reads a long
ushort ReadUInt16()
Reads a ushort
uint ReadUInt32()
Reads a uint
ulong ReadUInt64()
Reads a ulong
string ReadString()
Reads a string that has been written using a BinaryWriter.

==Read decimal, strings and char from a binary file using the BinaryReader==

<source lang="csharp">using System;
using System.IO;
static class MainClass
{
static void Main()
{
// Create a new file and writer.
using (FileStream fs = new FileStream("test.bin", FileMode.Create))
{
using (BinaryWriter w = new BinaryWriter(fs))
{
// Write a decimal, two strings, and a char.
w.Write(124.23M);
w.Write("Test string");
w.Write("Test string 2");
w.Write("!");
}
}
using (FileStream fs = new FileStream("test.bin", FileMode.Open))
{
using (StreamReader sr = new StreamReader(fs))
{
// Read the data and convert it to the appropriate data type.
fs.Position = 0;
using (BinaryReader br = new BinaryReader(fs))
{
Console.WriteLine(br.ReadDecimal());
Console.WriteLine(br.ReadString());
Console.WriteLine(br.ReadString());
Console.WriteLine(br.ReadChar());
}
}
}
}
}</source>
<pre class=codeResult>124.23
Test string
Test string 2
!</pre>

==Reset the file pointer to the start==

<source lang="csharp">using System;
using System.IO;
static class MainClass
{
static void Main()
{
// Create a new file and writer.
using (FileStream fs = new FileStream("test.bin", FileMode.Create))
{
using (BinaryWriter w = new BinaryWriter(fs))
{
// Write a decimal, two strings, and a char.
w.Write(124.23M);
w.Write("Test string");
w.Write("Test string 2");
w.Write("!");
}
}
using (FileStream fs = new FileStream("test.bin", FileMode.Open))
{
using (StreamReader sr = new StreamReader(fs))
{
using (BinaryReader br = new BinaryReader(fs))
{
Console.WriteLine(br.ReadDecimal());
Console.WriteLine(br.ReadString());
Console.WriteLine(br.ReadString());
Console.WriteLine(br.ReadChar());
}
// Read the data and convert it to the appropriate data type.
fs.Position = 0;
using (BinaryReader br = new BinaryReader(fs))
{
Console.WriteLine(br.ReadDecimal());
Console.WriteLine(br.ReadString());
Console.WriteLine(br.ReadString());
Console.WriteLine(br.ReadChar());
}
}
}
}
}</source>
<pre class=codeResult>124.23
Test string
Test string 2
!
Unhandled Exception: System.ObjectDisposedException: Cannot access a closed file.
at System.IO.__Error.FileNotOpen()
at System.IO.FileStream.Seek(Int64 offset, SeekOrigin origin)
at System.IO.FileStream.set_Position(Int64 value)
at MainClass.Main()</pre>

==Use BinaryReader to read file in binary format==

<source lang="csharp">using System;
using System.IO;
class MainClass
{
public static void Main()
{
FileStream outStream = File.Create("c:\\BinaryTest.dat");
BinaryWriter bw = new BinaryWriter(outStream);
bw.Write( (int) 3);
bw.Write( (decimal) 4.5);
string s = "Test String";
bw.Write(s);
bw.Flush();
bw.Close();
FileStream inStream = File.OpenRead("c:\\BinaryTest.dat");
BinaryReader br = new BinaryReader(inStream);
int i = br.ReadInt32();
decimal d = br.ReadDecimal();
string s2 = br.ReadString();
Console.WriteLine(i);
Console.WriteLine(d);
Console.WriteLine(s2);
br.Close();
}
}</source>
<pre class=codeResult>3
4.5
Test String</pre>

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