String to hex char array

Question

I get a string which is given as an argument to a function like e.g. 00112233445566778899aabbccddeeff and I need to make an unsigned char array of it which looks like this:

unsigned char array[16]= {0x00 ,0x11 ,0x22 ,0x33 ,0x44 ,0x55 ,0x66 ,0x77 ,0x88 ,0x99 ,0xaa ,0xbb ,0xcc ,0xdd ,0xee ,0xff};

I have no idea how to do it, tried some things with strcpy and thought about hex but this works only with << or >> as I know so I don't think I know how to apply it here. Anyone could help please?

You want to print all the characters of the string as hex values? — Borgleader, Jan 11 '15 at 00:58
You might get some ideas from this question: http://stackoverflow.com/questions/1070497/c-convert-hex-string-to-signed-integer The part you need to work out is how to convert 2 digits at a time. — Retired Ninja, Jan 11 '15 at 01:04
To the guy who deleted an answer don't worry, it's not my homework, it's just a small problem I had with a bigger program — Kala, Jan 11 '15 at 01:38

score 2 · Answer 1 · answered Jan 11 '15 at 01:05

2

It seems you need to convert each digit received to a nibble and to combine two nibbles into a byte. The conversion from digit to nibble can be done using a look-up or using conditional logic for digits and letters. The combination is a bitwise shift and a bitwise or.

I could write the code but I've somewhat outgrown assignments, not to mention that my version is unlikely to be a viable solution anyway.

answered Jan 11 '15 at 01:05

Dietmar Kühl

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"bitwise shit and a bitwuse or." autocowreck or just tired? :P – Borgleader Jan 11 '15 at 01:06
@Borgleader: Next time please wait until five minutes have passed before pointing out things like this! – Lightness Races in Orbit Jan 11 '15 at 01:09
@Mystical: it seems there is no edit history for the first 5 minutes or so: Borgleader would have needed to wait longer pointing it out... – Dietmar Kühl Jan 11 '15 at 01:10

Vincent Ho · Answer 2 · 2015-01-11T02:30:20.410

0

You could do this with a combination of istringstream and std::hex. example

#include <iostream>
#include <sstream>


int main() {
    std::string myStr = "1122AA010A";

    std::stringstream ss;
    int n;
    for(int i = 0; i<myStr.length(); ) {
        std::istringstream(myStr.substr(i,2))>>std::hex>>n;
        ss<<(char)n;
        i += 2;
        }

    std::string result = ss.str();

    std::cout<<"\n"<<result<<"\n";
    return 0;
    }

edited Jan 11 '15 at 02:30

answered Jan 11 '15 at 01:19

Vincent Ho

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7

How do I use std::hex when writing to an array? – Kala Jan 11 '15 at 01:21

String to hex char array

2 Answers2