修改代码，使用类。

下面是原始代码：

name = input("Enter your name: ")
age = int(input("Enter your age: "))
gender = input("Enter your gender: ")
height = float(input("Enter your height (in cm): "))
weight = float(input("Enter your weight (in kg): "))

bmi = weight / ((height/100)**2)

print(f"{name}, you are {age} years old, {gender}, your BMI is {bmi:.2f}")

下面是使用类的修改：

class Person:
    def __init__(self, name, age, gender, height, weight):
        self.name = name
        self.age = age
        self.gender = gender
        self.height = height
        self.weight = weight

    def calculate_bmi(self):
        return self.weight / ((self.height/100)**2)

    def display_info(self):
        bmi = self.calculate_bmi()
        print(f"{self.name}, you are {self.age} years old, {self.gender}, your BMI is {bmi:.2f}")

name = input("Enter your name: ")
age = int(input("Enter your age: "))
gender = input("Enter your gender: ")
height = float(input("Enter your height (in cm): "))
weight = float(input("Enter your weight (in kg): "))

person = Person(name, age, gender, height, weight)
person.display_info()

使用类的修改，将代码分为两个函数：一个用于初始化数据，另一个用于计算并显示BMI。类的初始化函数使用__init__方法，用于初始化对象的属性。计算BMI和显示信息的方法被封装到类中，以减少代码的重复和提高复用性。最后，通过创建一个Person对象来使用类。