Need to read hex values out of a file

This is a discussion on Need to read hex values out of a file within the C++ Programming forums, part of the General Programming Boards category; i am making a program that extracts certain hex values out of a file and saves in another file. but ...

  1. #1
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    Need to read hex values out of a file

    i am making a program that extracts certain hex values out of a file and saves in another file.

    but i have a problem, i don't know how to read hex values out of a file. i know how to read a regular text file but not hexidecimal. i need to place the file content in a variable and then separate the variable by offsets.

    thanks in advance for any help
    sorry if i sound stupid

  2. #2
    ZuK
    ZuK is offline
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    Try something like this
    Code:
    #include <string>
    #include <iostream>
    #include <iomanip>
    #include <sstream>
    
    using namespace std;
    
    int main() {
        char buffer [] ="0x1234 0x345";
        stringstream sstr( buffer );
        int word;
        sstr >> hex;
        while( sstr >> word ) {
            cout << word << " ";
        }
    }
    You could use a filestream instead of the stringstream
    Kurt

  3. #3
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    i really don't understand how that would work, where do i load the file? i just need to store the hex in a var from a file

  4. #4
    ZuK
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    Code:
    #include <string>
    #include <iostream>
    #include <iomanip>
    #include <fstream>
    
    using namespace std;
    
    int main() {
        ifstream fstr( "somefile.txt" );
        int word;
        fstr >> hex;
        while( fstr >> word ) {
            cout << word << " ";
        }
    }

  5. #5
    Hardware Engineer
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    ...i just need to store the hex in a var from a file
    Well, here's the thing.... You can't store a variable in hex! It's just a number.

    You can input a number in hex format, or display a number in hex, but in the computer's memory it's "just a number" (stored in binary, of course).

    Depending on what you're doing, you might find a Hex Editor useful. A hex editor allows you to view any file in hex, and edit the bytes. I use a hex editor called XVI32 (FREE !!!!).

    Most hex editors will also show the ASCII characters for any bytes that fall in the "ASCII range". Of course, the hex editor actually has no idea if a value of 65 (41 hex) represents the value 65 or the character 'A'.

    ...i know how to read a regular text file but not hexidecimal.
    Open your file in binary mode. In binary node, you can read-in the file as numbers. The term binary is a little misleading.... I consider it the "raw mode"

    Although the text mode is the default, it's a special case. Most file I/O is done in binary mode.
    Last edited by DougDbug; 05-05-2006 at 05:07 PM.

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