Integer to string template function

Convert any integer type, to any c++ string type (char or wchar_t) using this template function:

#include <string>
#include <algorithm>
#include <iostream>

template <typename Int_T, typename Char_T>
std::basic_string<Char_T> itoa(Int_T num, int base) {
	std::basic_string<Char_T> buf;
	buf.push_back(0);
	bool neg;
	
	if (num < 0) { neg = true; num *= -1; }
	
	int i, j;
	Char_T digits[36];
	for (j = 0, i = '0'; i <= '9'; i++, j++) digits[j] = i;
	for (i = 'a'; i <= 'z'; i++, j++) digits[j] = i;
	
	do {
		buf.push_back(digits[num % base]);
		num /= base;
	} while (num != 0);
	if (neg) buf.push_back('-');
	std::reverse(buf.begin(), buf.end());
	return buf;
}

int main() {
	std::wcout << L"-12 in binary is " <<
	itoa<int, wchar_t>(-12, 2) <<
	std::endl;
}