convert array numbers from binary to octal

[laura fidarova]

hi, ive asked this before and i know how to convert it now, thanks to the people that helped, but is there a way i can to it without using 'string', 't.length ; erase; empty' ? beacause i don't get how those work and bacically we haven't learned it for this question at school yet

Q: given an array that's formed from binary numbers, create a new array by converting the binary numbers of the first to octal

**also, i need to input the array from the console too

thanks in advance:)

  #include <iostream>
using namespace std;

int main()
{
    string s[3] = { "1101101","101","11" };
    string t;
    int d = 0;

    for (int i = 0;i < 3;i++) {
        t = s[i];
        s[i] = "";
        while (t.length() % 3 != 0)
            t.insert(0, "0");
        while (!t.empty()) {
            d = 0;
            d = 4 * (t[0] - '0') + 2 * (t[1] - '0') + (t[2] - '0');
            s[i] += d + '0';
            t.erase(0, 3);
        }
    }
    for (int i = 0;i < 3;i++)
        cout << s[i] << " ";

}

[seeplus]

So I guess my previous code using streams and the random class was no good either.

You should be using string to input the number, though. You can use a c-style string for input, but that really isn't good practice.

I'll have a look.......

[seeplus]

include <iostream>

int main()
{
	const int maxbin = 32;

	char inpbin[maxbin] {};

	std::cout << "Enter binary number (max " << maxbin - 1 << " digits): ";
	std::cin.getline(inpbin, maxbin);

	unsigned int dec {};

	for (char* inp = inpbin; *inp; dec = dec * 2 + *inp++ - '0');

	int octal {};

	for (int i = 1; dec != 0; i *= 10, dec /= 8)
		octal += (dec % 8) * i;

	std::cout << inpbin << " is " << octal << '\n';
}

Using char array instead of string. Note no input error checking

[laura fidarova]

@seeplus it was really good, much more practical i guess, but the teacher said i need to find another way to do it or else she'll deduct marks! :/

[seeplus]

else she'll deduct marks!

She should be encouraging you to get to understand what's already available within c++!

However, see my above post.

PS We don't know what's been covered in class - or how the teacher is expecting things to be done. Without existing code on which to guide, we can only provide sample code as we see the requirement.

[seeplus]

This may be the way she's expecting:

#include <iostream>

void digits(unsigned n, unsigned& dec)
{
	if (n >= 10)
		digits(n / 10, dec);

	dec = dec * 2 + n % 10;
}

int main()
{
	unsigned inpbin {}, dec {}, octal {};

	std::cout << "Enter binary number: ";
	std::cin >> inpbin;

	digits(inpbin, dec);

	for (unsigned i = 1; dec != 0; i *= 10, dec /= 8)
		octal += (dec % 8) * i;

	std::cout << "Binary " << inpbin << " is " << octal << " Octal\n";
}

NOTE No error checking!

[laura fidarova]

@seeplus thank you sooo much!!:)