python学习--函数例子

#!/usr/bin/env python3
# -*- coding:utf-8 -*-

#01 函数的定义，调用
#生日歌
def happy():
    print("Happy birthday to you!")
 
def sing(person):
    happy()
    happy()
    print("Happy birthday, dear", person + "!")
    happy()

def main():
    sing("Mike")
    print()
    sing("Lily")
    print()
    sing("Elmer")

main()


'''
02 改变参数值的函数：
    函数的形参只接收了实参的值，给形参赋值并不影响实参
    Python可以通过值来传递参数
什么是函数的形参 和 实参？
    一种是函数定义里的形参，一种是调用函数时传入的实参
'''

#例1 利息计算 addinterest1.py
def addInterest(balance,rate): # balance 和 rate 是函数addInterest的形参
    newBalance = balance * (1 + rate)
    balance = newBalance

def main():
    amount =1000
    rate = 0.05
    addInterest(amount,rate)  #amount 和rate 是函数addInterest 的实参
    print(amount)

main()

#例2 利息计算 addinterest2.py

def addInterest(balance, rate):
    newBalance = balance * (1 + rate)
    return newBalance

def test():
    amount = 1000
    rate = 0.05
    amount = addInterest(amount, rate)
    print(amount)

test()

#例3： 处理多个银行账户的程序
#addInterest3.py
def createTable(principal, apr):
    #为每一年绘制星号的增长图
    for year in range(1,11):
        principal = principal * (1 + apr)
        print("%2d"%year, end = "")
        total = caulateNum(principal)
        print("*" * total)
    print("0.0k        2.5k    5.0k    7.5k    10.0k")
def caulateNum(principal):
    #计算星号数量
    total = int(principal * 4 / 1000.0)
    return total
def main():
    print("This program plots the growth of a 10-year investment.")
    # 输入本金和利率
    principal = eval(input("Enter the init principal: "))
    apr = eval(input("Enter the annualized interest rate: "))
    #建立图表
    createTable(principal,apr)
main()