Concatenate array of unsigned chars

[Alexkid]

Hi there,

I have an array of unsigned chars SOURCE, i need to combine into DESTINATION, i want to turn:

SOURCE[0] = 3
SOURCE[1] = 9
SOURCE[2] = ' '
SOURCE[3] = 0
SOURCE[4] = 4
SOURCE[5] = ' '
SOURCE[6] = 7
SOURCE[7] = d

into

DESTINATION[0] = 39
DESTINATION[1] = 04
DESTINATION[2] = 7d

Any ideas

Many Thanks

[Lucaci Andrew]

You could do it by using some strings, streamstrings and vectors...

#include <iostream>
#include <sstream>
#include <string>
#include <vector>
using namespace std;

#define SIZE 8

int main(){
    unsigned char SOURCE[SIZE]={'3', '9', ' ','0','4',' ','7','d'};
    vector<string> destination;
    string part;
    stringstream token;
    token<<SOURCE;
    while(getline(token, part, ' ')) destination.push_back(part);
    for (size_t i=0;i<destination.size();i++)
        cout<<destination[i]<<endl;
    return 0;
}

[deceptikon]

Somehow I get the impression that he wants numeric values rather than strings. In that case it would be necessary to either convert the string to a number or build the number directly. For example:

#include <algorithm>
#include <cctype>
#include <iostream>
#include <string>

int digit_value(char ch)
{
    const std::string digits = "0123456789abcdef";
    std::string::const_iterator it = std::find(digits.begin(), digits.end(), ch);

    if (it == digits.end())
        return -1;

    return it - digits.begin();
}

int main()
{
    const char *src = "39 04 7d";

    while (*src) {
        if (isspace(*src)) {
            ++src;
            continue;
        }

        unsigned char value = 0;

        value = digit_value(*src++);
        value = 16 * value + digit_value(*src++);

        std::cout<< (int)value <<'\n';
    }
}

[Gonbe]

#include <sstream>
#include <iostream>

int main()
{
    const char *src = "39 04 7d";
    int value;
    std::stringstream ss;

    ss << std::hex << src;

    while (ss >> value)
        std::cout << value << std::endl;

    return 0;
}

-edit-

Added a return 0. (Blame deceptikon's code for lacking that, got lazy and took that as base)
Also works with upper case. (e.g. "FF" vs "ff")

[Alexkid]

Thanks for your prompt replys.

Unfortunalty i do no get to specify what "src" is. All i have is unsigned char SOURCE[8] which i need to fit into DESTINATION[3].

The reason being a function takes unsigned char DESTINATION[3].

deceptikon: thanks for that, but i'm unable to match my SOURCE[8] to the const char *src you have used.

Thanks

[Ancient Dragon]

Then just change his code like this: (notice it should be 9 instead of 8)
char SOURCE[9] = "39 04 7d";

[Gonbe]

Even if that's not possible, you could change it to something like this:

#include <sstream>
#include <iostream>

const int SOURCE_SIZE      = 8;
const int DESTINATION_SIZE = (SOURCE_SIZE + 1) / 3;

int main()
{
    std::stringstream ss;
    int value;

    unsigned char SOURCE     [SOURCE_SIZE]      = {'3', '9', ' ', '0', '4', ' ', '7', 'D'};
    unsigned char DESTINATION[DESTINATION_SIZE] = { 0 };

    ss << std::hex;
    ss.write((const char*)SOURCE, SOURCE_SIZE);

    for (int i = 0; ss >> value; i++)
        DESTINATION[i] = value;

    return 0;
}

-edit-
Modified it so the destination size is based on the source size.. Just set source to 8 for your example, destination will be 3 then.

[Alexkid]

I don't understand, applogies i'm fairly new to c++.

i dont get to specify

const char *src = "39 04 7d";

As the data is in an unsigned char array of [8] which i get passed. Changing deceptikon's code to the above get me into a whole of pain with the *src pointer and i already have a SOURCE[8] anyway.

Thanks

[Alexkid]

Thanks Gonbe,

nearly, couldn't get it to work with letters, the 'D' seems to get missed out

Thanks

Alex

[Gonbe]

nearly, couldn't get it to work with letters, the 'D' seems to get missed out

What do you mean?

When I add something like the following after my code:

for (int i = 0; i < DESTINATION_SIZE; i++)
    std::cout << (int)DESTINATION[i] << std::endl;

You'd get the following output:

57
4
125

Which is what I'd expect.

[NathanOliver]

What is the type of DESTINATION?

[Gonbe]

What is the type of DESTINATION?

The reason being a function takes unsigned char DESTINATION[3].

[deceptikon]

deceptikon: thanks for that, but i'm unable to match my SOURCE[8] to the const char *src you have used.

It was an example only, I'm not doing your work for you. You'll obviously need to adjust the algorithm to suit your source and destination arrays.