如何在没有stdlib的情况下将int转换为string？

def int_to_string(num):
    if num == 0:
        return "0"
    
    is_negative = False
    if num < 0:
        is_negative = True
        num = abs(num)
    
    result = ""
    while num > 0:
        digit = num % 10
        result += chr(ord('0') + digit)
        num //= 10
    
    if is_negative:
        result += "-"
    
    return result[::-1]

# 示例用法
num = -123
result = int_to_string(num)
print(result)  # 输出: "-123"

def int_to_string(num):
    if num == 0:
        return "0"
    
    is_negative = False
    if num < 0:
        is_negative = True
        num = abs(num)
    
    result = ""
    if num > 0:
        result = int_to_string(num // 10)
    
    result += chr(ord('0') + num % 10)
    
    if is_negative:
        result = "-" + result
    
    return result

# 示例用法
num = -123
result = int_to_string(num)
print(result)  # 输出: "-123"