Hex manipulations - c++

Question

There are very nice Hex.Decode(string hexString) and Hex.ToHexString(byte[] hexArray) methods in BouncyCastle crypto library (C#, Java).
How to make the same conversions with CString variable, that stores hex-string for example "af010cdb" to unsigned char* and vice-versa in C++?

Answer 1

These are real easy to implement:
CString ToHexString(const CByteArray& Array)
{
CString sHexString;
for (int i=0; i<Array.GetSize(); i++)
sHexString.AppendFormat(_T("%02X"), Array[i]);
return sHexString;
}
void DecodeHexString(const CString& sHexString, CByteArray &Array)
{
if (sHexString.IsEmpty())
return;
int nLen = sHexString.GetLength();
if ((nLen % 2) != 0)
{
ASSERT(FALSE);
return;
}
Array.SetSize(nLen/2);
int nByte = 0;
for(int i=0; i<nLen; i += 2)
{
CString sByte = sHexString.Mid(i, 2);
BYTE byte = (BYTE)_tcstol(sByte, NULL, 16);
Array[nByte] = byte;
nByte++;
}
}

Answer 2

You can also use std::string and std::vector<unsigned char>
Edit: removed sscanf and sprintf
std::vector<unsigned char> str_to_byte(std::string str)
{
std::vector<unsigned char> bytes;
std::stringstream ss(str);
std::string part;
while (ss >> std::setw(2) >> part)
{
try {
int i = std::stoi(part, 0, 16);
bytes.push_back(static_cast<unsigned char>(i));
}
catch (...) {//error msg
}
}
return bytes;
}
std::string byte_to_str(std::vector<unsigned char> bytes)
{
std::stringstream ss;
ss << std::hex << std::setfill('0') << std::uppercase;
for (auto c:bytes)
ss << std::setw(2) << static_cast<unsigned int>(c);
return ss.str();
}
int main()
{
std::vector<unsigned char> bytes = str_to_byte("EF010203A0A1FFz");
std::string str = byte_to_str(bytes);
cout << str << endl; //should print "EF010203A0A1FF"
return 0;
}