Question

I wrote a very simple encryption program to practice c++ and i came across this weird behavior. When i convert my char* array to a string by setting the string equal to the array, then i get a wrong string, however when i create an empty string and add append the chars in the array individually, it creates the correct string. Could someone please explain why this is happening, i just started programming in c++ last week and i cannot figure out why this is not working.

Btw i checked online and these are apparently both valid ways of converting a char array to a string.

void expandPassword(string* pass)
{
    int pHash = hashCode(pass);
    int pLen = pass->size();
    char* expPass = new char[264];
    for (int i = 0; i < 264; i++)
    {
        expPass[i] = (*pass)[i % pLen] * (char) rand();
    }
    string str;
    for (int i = 0; i < 264; i++)
    {
        str += expPass[i];// This creates the string version correctly
    }

    string str2 = expPass;// This creates much shorter string
    cout <<str<<"\n--------------\n"<<str2<<"\n---------------\n";

    delete[] expPass;
}

EDIT: I removed all of the zeros from the array and it did not change anything

Answer 1

When copying from char* to std::string, the assignment operator stops when it reaches the first NULL character. This points to a problem with your “encryption” which is causing embedded NULL characters.

This is one of the main reasons why encoding is used with encrypted data. After encryption, the resulting data should be encoded using Hex/base16 or base64 algorithms.