Question

string to_binary(char c)

returns 5 bit string that is the index of the character argument.

if the provided character is not a lower-case alphabetic character, return the empty string.

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char from_binary(string bit_str)

returns the character that the 5 bit binary string bit_str represents.

if any of the following conditions are not true:

 the size of bit_str is 5

 every element of bit_str must be a ‘1’ or a ‘0’

 the character produced must be a lower case letter return the character 0 (the NULL char).

C++ functions help please

Answer 1

char from_binary(string bit_str) {
    char c;
    if (bit_str.size() != 5)
        return NULL;
    else {
        int num = 0;
        for (auto i = 0; i < bit_str.size(); ++i) {
            if (bit_str[i] == '0' or bit_str[i] == '1') {
                if (bit_str[i] == '0')
                    num += 0 * pow(2, 4 - i);
                if (bit_str[i] == '1')
                    num += 1 * pow(2, 4 - i);
            }
        }
        c = 'a' + num;
    }
    if (islower(c))
        return c;
    return NULL;
}