int64
last_digit(int64 n) {
    int64 m = n / (int64)10;

    m *= (int64)10;
    return n - m;
}

char
todigit(int64 n) {
    static char digits[] = "0123456789";
    return digits[n];
}

string
FormatMoney(int64 n, bool fPlus)
{
    string str;
    bool was_negative = n<0;
    bool omit_digit = true;     // Omit trailing zeros.
    size_t ix=0;

    if(n == 0) {
        str.insert(0,1,'0');
        return str;
    }
    if(n < 0) {
        n = -n;
    }
    // Process the number from right to left.
    for(ix=0; n || ix<8; ix++) {
        int64 next = last_digit(n);
        n /= (int64)10;
        if(next || ix>=8) omit_digit=false;
        if(!omit_digit) {
            str.insert(0,1,todigit(next));
            if(ix == 7) str.insert(0,1,'.');
        }
    }

    if(was_negative) str.insert(0,1,'-');
    else if(fPlus) str.insert(0,1,'+');
    return str;
}