Matching user input to char array (Both contain DEL chars)

Question

Im currently solving a binary bomb. Within there is a phase with the following code:

bool phase_bird(const char* guess)
{
    char c;
    c=blackBoxC();
    appendChar(c);
    mute(true);
    c=blackBoxC();
    appendChar(c);
    c=blackBoxC();
    appendChar(c);
    mute(false);
    c=blackBoxC();
    appendChar(c);
    c=blackBoxC();
    appendChar(c);
    mute(false);
    c=blackBoxC();
    appendChar(c);
    c=blackBoxC();
    appendChar(c|3);
    c=blackBoxC();
    appendChar(c|5);
    c=blackBoxC();
    appendChar(c|9);
    return stringMatches(guess);
}

what i know so far is that:

• blackBoxC() returns a char

• appendChar() appends the char to the char array which will be compared to the user input

• mute() while true stops appendChar() from working

i currently know that the chars returned by blackBoxC() are yxFUOXizu, with only yUOXkizv appending.

i also know that the last three chars are changed from izv to k^?^? as a result of the bitwise OR.

HOWEVER, it seemed all straight forward id simply just enter yUOXk^?^? as my guess. BUT the guess was invaild and the bomb exploded. I didnt realise that entering these DEL char would actually delete some of my input.

changing it from yUOXk^?^? to yUO

Now each invaild guess actually cuases me to loose marks, which is a problem! i have no idea what method they are using to compare the char arrays, but im assuming it is probably strcmp().

This means that even if i was to for example change my input to yUOXkkk^?^? the strings would still be different lengths.

If anyone has any input on how to solve this problem id love to hear it!

regards