reading HEX characters

[ayush20m]

I am trying to read from a HEX file. I am unable to compare a certain characters from the HEX, can anyone tell me what I am doing wrong?

if (line[i] == 0x88 && line[i+1] == 0xE7){
				wiFlag++;
				lowLim = i;		
			}

When I check 0x01 or 0x04, it works, but not for the above ones

[Null]

You are comparing signed and unsigned numbers:

#include <iostream>
using namespace std;

unsigned char y=0xE5; // unsigned char can store values between 0 and 255
char x=0xE5; // signed char can store values between -128 and +128, so 0xE5 becomes -27



int main()
{

if(x==0xE5) cout <<"X is equal to 0xE5"; // comparing -27 and 0xE5
if(y==0xE5) cout <<"Y is equal to 0xE5"; // comparing  

cout <<endl;
cout <<"x== "<<(signed)x<<endl; 
cout <<"y== "<<(unsigned)y<<endl;

}

So simply declare line as unsigned char instead of char

[ayush20m]

Thank you for the quick reply. for me line is String and not Char. Can I do the same for it too?

[Null]

You shouldn't use binary file IO and strings together.
Here's an example how to do this properly:

#include <fstream>
#include <csignal>
#include <iostream>
using namespace std;




int main()
{
fstream file("hex.dat");

// get file size
file.seekg(0,ios::end);
int file_size=file.tellg();
file.seekg(0,ios::beg);

cout <<"File size : "<<file_size<< "bytes"<<endl;

unsigned char *data=new unsigned char [file_size]; // allocate space for file

file.read( (char*)data,file_size);

for(int i=0;i<file_size;i+=2)
  {
      if (data[i] == 0x88 && data[i+1] == 0xE7)
           {
				// your code here
			}
  }


delete[] data;
file.close();
}

http://www.cplusplus.com/reference/iostream/fstream/
http://www.cplusplus.com/reference/iostream/istream/read/
Hope this helps.