Base62 encoding in various languages

base62.h

#ifndef base62_h
#define base62_h

#include <string>

/** Returns base 62 encoded unsigend integral value.
 *  base62(1234567890) // -> s"1ly7vk"
 */
std::string base62(unsigned long long value)
{
    static const std::string alphabet{"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"};
    static const std::size_t base = alphabet.size();
    std::string result{};
    while(value)
    {
        result.insert(0, alphabet.substr(value % base, 1));
        value /= base;
    }
    return result.size() ? result : alphabet.substr(0, 1);
}

#endif

base62.py

import string

def base62(value):
    """Returns base 62 encoded unsigend integral value.
    >>> base62(1234567890)
    '1ly7vk'
    """
    value = abs(value) # unsigned!
    alphabet = string.digits + string.letters
    base = len(alphabet)
    result = []
    while value:
        result.insert(0, alphabet[value % base])
        value /= base
    return ''.join(result) if result else alphabet[0]