C++ easy way to convert int to string with unknown base

Question

Here is code in Java:

int a = 456;
int b = 5;
String s = Integer.toString(a, b);
System.out.println(s);

Now I want the same in C++, but all the conversions i find convert to base 10 only. I ofc dont want to implement this by mysleft, why to write something what already exists

`itoa()` in `` will allow you to specify the base (between 2 - 36).. — Nim, Dec 06 '13 at 15:31
_don't want to implement this by myself_. I remember this as a common assignment in beginning programming classes, so any real programmer shouldn't consider it a burden. — Barmar, Dec 06 '13 at 15:33
Implement it yourself. It's relatively simple, so you should know how to do this. What if you had a job interview? After that, you can use something better, but you SHOULD be able to reinvent a simple wheel, even if you will later buy a better-designed wheel. — leewz, Dec 06 '13 at 15:39
@Nim, itoa isn't standard C++. It doesn't seem to be standard C either. — leewz, Dec 06 '13 at 15:40
how do i possible duplicate: http://stackoverflow.com/questions/3225130/c-base-conversion — leewz, Dec 06 '13 at 15:41

score 2 · Accepted Answer · answered Dec 06 '13 at 15:48

2

although std::strtol is more flexible, in a controlled case you can use itoa as well.

int a = 456;
int b = 5;
char buffer[32];
itoa(a, buffer, b);

answered Dec 06 '13 at 15:48

yildirim

316
7
14

1

buffer size should be 33 – Artur Dec 06 '13 at 16:42
Reference to https://stackoverflow.com/questions/3799595/itoa-function-problem, it seems itoa can't be used int C++. – keineahnung2345 Feb 28 '20 at 03:28
@keineahnung2345 I think it's not available under Linux, only MS-Windows. – Alexis Wilke Sep 01 '23 at 02:03

score 1 · Answer 2 · edited May 23 '17 at 12:29

1

If you want base 8 or 16 you can easily use the string manipulators std::oct and std::hex. If you want arbitrary bases, I suggest checking out this question.

edited May 23 '17 at 12:29

Community

1
1

answered Dec 06 '13 at 15:30

KitsuneYMG

12,753
4
37
58

score 1 · Answer 3 · answered Dec 06 '13 at 16:12

Without error handling http://ideone.com/nCj2XG:

char *toString(unsigned int value, unsigned int radix)
{
    char digit[] = "0123456789ABCDEFGHIJKLMNOPRSTUVWXYZ";
    char stack[32];
    static char out[33];

    int quot, rem;
    int digits = 0;

    do
    {
        quot = value / radix;
        rem = value % radix;

        stack[digits] = digit[rem];
        value = quot;
        digits++;
    }
    while( value );

    int i = 0;
    while(digits--)
    {
        out[i++] = stack[digits];
    }

    out[i] = 0;

    return out;
}

Dmitrii Guliagin · Answer 4 · 2019-09-30T08:04:19.243

1

There is no standard function itoa, which performs conversion to an arbitrary calculus system. But for example, in my version of the compiler there is no implementation. My solution:

#include <string>

// maximum radix - base36
std::string int2string(unsigned int value, unsigned int radix) {
    const char base36[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    std::string result;
    while (value > 0) {
        unsigned int remainder = value % radix;
        value /= radix;
        result.insert(result.begin(), base36[remainder]);
    }
    return result;
}

edited Sep 30 '19 at 08:04

answered Sep 30 '19 at 07:37

Dmitrii Guliagin

71
1
4

While this code may answer the question, providing additional context regarding why and/or how this code answers the question improves its long-term value. – xiawi Sep 30 '19 at 07:56
Thanks for the feedback. Made changes to the answer. – Dmitrii Guliagin Sep 30 '19 at 08:05

C++ easy way to convert int to string with unknown base

4 Answers4