Parse Binary for Hex Value

[Rehorav]

Hey everyone, I'm trying to parse a binary file for a certain file, and I found a way but its a inefficient. Basically, what I'm trying to do is find a value, and then write over it. But right now I'm just finding the value. Here is the code, hopefully someone can give me a suggestion to make it so I can just search for the entire value instead of byte by byte.

int main ()
{
	FILE *File1;

	if ( ( File1 = fopen ( "App.exe", "rb" ) ) == NULL )
	{
		MessageBox ( NULL, "Can't Open First File", "Messup", NULL );
	}

	unsigned char Char1;

	int Loc = 0;

	while ( !feof ( File1 ) ) 
	{
		Char1 = fgetc ( File1 );
		if ( Char1 == 0xDD )
		{
			Loc = 1;
		}
		else if ( Char1 == 0xCC && Loc == 1 )
		{
			Loc = 2;
		}
		else if ( Char1 == 0xBB && Loc == 2 )
		{
			Loc = 3;
		}
		else if ( Char1 == 0xAA && Loc == 3 )
		{
			MessageBox ( NULL, "Found", "Found", NULL );
		}
		else
		{
			Loc = 0;
		}
	}
}

As you can tell, I'm looking for 0xAABBCCDD (endian ordering of course).

As I said, its very inefficient. If someone could tell me how to find the whole value at once, that would be amazing .

And can someone tell me how to write over that value once I find it?

And if you're wondering why I'm doing this, its an experiment I'm trying with finding values with files. Kind of a boring Saturday so why not .

[D_Drmmr]

As I said, its very inefficient. If someone could tell me how to find the whole value at once, that would be amazing .

Just use fread.

And can someone tell me how to write over that value once I find it?

Just use fwrite.

[Rehorav]

Ah alright thank you! I've been googling about looking for how to search for an exact value with fread, but I couldn't find anything to help me .

[alanjhd08]

Hi,

You might also want to read the whole file, or blocks of it, into a memory buffer, then search through that. You will be able to test for 4 bytes at a time

Alan

[Rehorav]

I have been looking around on how I would read the file then search for the value, I'm still stumped . I get how to open a file, but I don't get how to look for that exact value.