减少重复代码

使用函数或类，将重复代码封装起来供多处调用。

例如，以下是一个重复代码较多的程序：

def calculate_circle_area(radius):
    pi = 3.14
    return pi * radius ** 2

def calculate_triangle_area(base, height):
    return 0.5 * base * height

def calculate_rectangle_area(length, width):
    return length * width

# 计算圆形、三角形、矩形的面积
radius1 = 3
circle_area1 = 3.14 * radius1 ** 2

base1 = 5
height1 = 2
triangle_area1 = 0.5 * base1 * height1

length1 = 4
width1 = 6
rectangle_area1 = length1 * width1

# 计算不同输入下的圆形、三角形、矩形的面积
radius2 = 4
circle_area2 = 3.14 * radius2 ** 2

base2 = 7
height2 = 3
triangle_area2 = 0.5 * base2 * height2

length2 = 5
width2 = 7
rectangle_area2 = length2 * width2

可以将重复计算面积的代码改成函数：

def calculate_circle_area(radius):
    pi = 3.14
    return pi * radius ** 2

def calculate_triangle_area(base, height):
    return 0.5 * base * height

def calculate_rectangle_area(length, width):
    return length * width

# 计算圆形、三角形、矩形的面积
radius1 = 3
circle_area1 = calculate_circle_area(radius1)

base1 = 5
height1 = 2
triangle_area1 = calculate_triangle_area(base1, height1)

length1 = 4
width1 = 6
rectangle_area1 = calculate_rectangle_area(length1, width1)

# 计算不同输入下的圆形、三角形、矩形的面积
radius2 = 4
circle_area2 = calculate_circle_area(radius