python基础1

1.输入一个数字，判断返回-- input, if

num = int(input("Enter: "))     #输入一个数字

if num <= 100:

   print("...")

else:

2.循环倒叙输出20个数字-- while, w -= 1

w = 20
while w > 1:
    print(w)
    w -= 1        #w -= 1相当于 w = w - 1

3.计算银行存钱本息和-- str.format，{:.2f}

#!/usr/bin/env python3

amount = float(input("Enter amount: ")) # 输入数额 

inrate = float(input("Enter Interest rate: ")) # 输入利率 
period = int(input("Enter period: ")) # 输入期限 
value = 0 
year = 1 
while year <= period: 
    value = amount + (inrate * amount)
    print("Year {} Rs. {:.2f}".format(year, value))
    amount = value 
    year = year + 1


知识点：
--str.format()
print("my name is {0}, age is (1).".format('zpp',18))  #单引号双引号都可以,{0}必须从0开始
--{:.2f}   保留小数点后两位

4.求3个数的平均值-- 

#!/usr/bin/env python3
N = 10
sum = 0
count = 0
print("please input 10 numbers:")
while count < N:
    number = float(input())
    sum = sum + number
    count = count + 1
average = sum / N
print("Average = {:.2f}".format(average))

5.温度转换表

#!/usr/bin/env python3
fahrenheit = 0
print("Fahrenheit Celsius")
while fahrenheit <= 250:
    celsius = (fahrenheit - 32) / 1.8 # 华式转摄氏公式C=(F-32)/1.8
    print("{:5d} {:7.2f}".format(fahrenheit , celsius))
    fahrenheit = fahrenheit + 25

知识点：
{:5d}   意思是替换为5个字符宽度的整数，后对齐
{:7.2f} 意思是替换为7个字符宽度且保留2位小数的整数