problems encrypting char* - c++

Question

i have been working on this project for a week and i cant find the solution to my problems.
i'm making an encryptor which can encrypt/decrypt binary file(like .exe, .jpg etc).
i am able to correctly get the data from the binary file using vector.
but i cannot correctly encrypt/decrypt the data from the vector.
some code:
if (encryptFile)
{
Crypt crypt;
//TOencryptfile.open(writeFile, ios::binary | ios::out);
vector<char> buffer((istreambuf_iterator<char>(encryptFile)),(istreambuf_iterator<char>()));
cout << buffer.size() << endl;
_getch();
for (std::vector<char>::iterator i = buffer.begin(); i != buffer.end(); ++i) {
// encryption that fails
temp = crypt.getKeyFromString(&*i , key, strlen(&*i));
}
TOencryptfile.close();
encryptFile.close();
}
and the function getKeyFromString:
KEYCRYPT Crypt::getKeyFromString(KEYCRYPT text, KEYCHAR charkey, keylength length) {
int string_size = std::strlen(text);
KEYCRYPT textcrypt = new char[string_size + 1];
std::strcpy(textcrypt, text);
int key = strlen(charkey);
for (int i = 0; i < length; i++) {
if (strlen(text) != 0) {
textcrypt[i] = text[i] ^ charkey[i % (sizeof(charkey) / sizeof(char))];
//keylvl += text[i] ^ (int(charkey) + i) % key;
//keyfnl += keylvl[i] ^ (int(charkey) - i) * key;
}
}
return textcrypt;
}
and at last the types:
typedef char* KEYCRYPT;
typedef int KEY;
typedef char* KEYCHAR;
typedef int keylength;
does anybody know a good way to encrypt *i?
because my way does not work, it does not return the same when calling the function again with getKeyFromString(temp, key, strlen(temp))

Answer 1

well, according to the response of #Barmar:
#waterlight Put the file contents into a string and pass that to the crypto API.
i managed to fix the problem.
all i had to do was:
stringstream result;
std::copy(buffer.begin(), buffer.end(), std::ostream_iterator<char>(result, " "));
string now = result.str();
and everything worked.
thanks to everybody who replied!!