Python 基础之三条件判断与循环

If……else 基本结构：

If condition:

do something

else:

do something

或者

If condition:

do something

elif condition:

do something

else:

do something

Python 通过缩进来确定一段代码的作用域，同一级别的代码缩进要保持一致，官方建议是4个空格。

提示：IndentationError，都为代码中存在缩进错误。

小练习：

# 猜luck number,n=6

# 猜的数字比6大，提示小一点

# 猜的数字比6小，提示大一点

#猜的数字等于6，提示Bingo

代码：

 #!user/bin/env python3
 # -*- coding: gbk -*-
 luck_num = 19
 input_num = int(input("please input the luck num:"))
 if input_num == 19:
     print("Bingo!")
 elif input_num > luck_num:
     print("the num is Bigger!")
 else:
     print("the num is smaller")

引入循环while，加入次数限制，代码：

 #!user/bin/env python3
 # -*- coding: gbk -*-
 luck_num = 19
 input_num = int(input("please input the luck num:"))
 if input_num == 19:
     print("Bingo!")
 elif input_num > luck_num:
     print("the num is Bigger!")
 else:
     print("the num is smaller")

For 循环方式：

 for num_of_times in range(3):
     # When failure exit after three times.
     input_num = int(input("please input the luck num:"))
     if input_num == 19:
         print("Bingo!")
         break
     elif input_num > luck_num:
         print("the num is Bigger!")
     else:
         print("the num is smaller")
 else:
     print("you try too many times.")

continue，跳过

break，中断

 for i in range(10):
     if i < 5:
         continue
     print(i)

 #result
 5
 6
 7
 8
 9

continue 和 break的区别

continue 是跳过当前循环块的剩余语句，进行下一次循环。break 是跳出当前循环块，停止当前循环。