CODEWITHSUNDEEP
c++
malw guy
malw guy

Reputation: 1

Interchanging offset values in a binary file

Recently I've been working on some scripts, and today I encountered a little problem, I would like to interchange the values of 2 offsets of a binary file. Like interchanging the value of the position 0x00 with the value of 0x01, I tried with file.seekp(0x00) and then get the value, hold it in a char, and later to insert the value on the position 0x01 I used file.seekp(0x01) and then file.put(char), but the main problem is that it's not modifying the value of 0x01, just adds the char to it.

Is there any way I could modify it's value ?

before attempting to interchange the first two offsets values : before attempting to interchange the first two offsets values

after attempting to interchange the first two offsets values : after attempting to interchange the first two offsets values

And basically, what I need is to interchange them, not to add to the second offset the first's value .

The code I used :

char c[1];
fstream file(path, ios::in | ios::out | ios::binary );
file.seekp(0x00);
c[0] = file.get();
    
file.seekp(0x01); 
c[1] = file.get(); 
file.put(c[0]); 

file.seekp(0x00);
file.put(c[1]);

Upvotes: 0

Views: 157

Answers (1)

Jérôme Richard
Jérôme Richard

Reputation: 50846

c should be of size 2 and get/put move the file cursor leading to the issue. Here is the corrected code:

char c[2];
fstream file("test", ios::in | ios::out | ios::binary);

file.seekp(0x00);
c[0] = file.get();
c[1] = file.get();

file.seekp(0x00);
file.put(c[1]);
file.put(c[0]);

Upvotes: 1

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