CODEWITHSUNDEEP
c#binaryhex
Jovan Marković
Jovan Marković

Reputation: 19

write hex data to file at specific address c#

I need help to write hex data AB at adress 0x0156 in binary file in c#. What i used BinaryWriter gives wrong data 00.

BinaryWriter bw = new BinaryWriter(File.OpenWrite(path));
bw.Write("AB");
bw.Dispose();

Upvotes: 0

Views: 1738

Answers (1)

PaulF
PaulF

Reputation: 6773

If you need to write it at address 0x156 you need to move there first using the Seek method. You also need to write a byte value rather than a string. 

BinaryWriter bw = new BinaryWriter(File.OpenWrite(path));
bw.Seek(0x156,SeekOrigin.Begin);
bw.Write((byte)0xab);
bw.Dispose();

If the file does not exist, or is shorter than 343 bytes, it will be padded with 0 values up to the 342nd byte.

If you want to write a number of bytes starting from a particular location you could do something like this :

int StartLocation = 0x202;
int EndLocation = 0x30b;
byte ValueToWrite = 0xFF;
BinaryWriter bw = new BinaryWriter(File.OpenWrite(path));
bw.Seek(StartLocation,SeekOrigin.Begin);
for (int CurLocation = StartLocation; CurLocation <= EndLocation; CurLocation++)
  bw.Write(ValueToWrite);
bw.Dispose();

Another way would be 

int StartLocation = 0x202;
int EndLocation = 0x30b;
byte ValueToWrite = 0xFF;
byte [] ByteArray = new byte[EndLocation-StartLocation+1];
for (int i = 0; i < ByteArray.Length; i++)
  ByteArray[i] = ValueToWrite;
BinaryWriter bw = new BinaryWriter(File.OpenWrite(path));
bw.Seek(StartLocation,SeekOrigin.Begin);
bw.Write(ByteArray);
bw.Dispose();

Upvotes: 4

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