把加减乘除函数都整合进去形成完整的64位减乘除计算器，并优化一下使结构更清晰，便于理解

为了创建一个完整的64位算术计算器，我们将把加、减、乘、除四个基本运算功能整合到一个模块中，保持代码结构清晰。这里是一个简化版的示例，使用Python来实现：

class Calculator:
    def __init__(self, max_value=2**64 - 1):
        self.max_value = max_value
        self.supported_operations = ['+', '-', '*', '/']

    def validate_input(self, num1, num2, op):
        try:
            num1 = int(num1)
            num2 = int(num2)
        except ValueError:
            return False
        if not isinstance(op, str) or op not in self.supported_operations:
            return False
        return abs(num1) <= self.max_value and abs(num2) <= self.max_value

    def add(self, num1, num2):
        return num1 + num2

    def subtract(self, num1, num2):
        return num1 - num2

    def multiply(self, num1, num2):
        return num1 * num2 % (self.max_value + 1)

    def divide(self, num1, num2):
        if num2 == 0:
            raise ValueError("除数不能为零")
        quotient = num1 // num2
        remainder = num1 % num2
        return quotient, remainder

    def calculate(self, expression):
        tokens = expression.split()
        if len(tokens) != 3:
            return "语法错误"
        
        operator, num1, num2 = tokens[0], tokens[1], tokens[2]
        if not self.validate_input(num1, num2, operator):
            return "输入错误"

        if operator == '+':
            result = self.add(int(num1), int(num2))
        elif operator == '-':
            result = self.subtract(int(num1), int(num2))
        elif operator == '*':
            result = self.multiply(int(num1), int(num2))
        elif operator == '/':
            quotient, remainder = self.divide(int(num1), int(num2))
            result = f"商：{quotient}, 余数：{remainder}"
        else:
            return "不支持的操作"

        return result

# 使用示例
calculator = Calculator()
expression = "50 * 7 / 3"
result = calculator.calculate(expression)
print(result)

这个`Calculator`类包含了所有必要的方法，包括验证输入、加减乘除等。用户可以通过构造函数设置最大值，然后使用`calculate`方法传入表达式来获取结果。这样，整个计算器的结构就比较清晰，易于理解和维护。