Python05:while循環

時間 2019-11-15

原文原文鏈接

If…else的進階，用幾個程序來實現講解。python

用if猜數字：spa

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:Mclind

age = 56

guess_age = int(input("guess age:"))

if guess_age == age:
    print("yes, you got it.")
elif guess_age > age:
    print("think smaller...")
else:
    print("think bigger...")code

輸出：utf-8

guess age:23input

think bigger...it

解釋：table

如要須要判斷多個條件，在if…else中添加elif，須要多少添加多少，如上文程序。class

可是，這樣程序只能執行一次就結束了，加入次數條件控制（程序的循環執行）。cli

while實現循環：coding

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:Mclind

count = 0
while True:
print("count:", count)
count = count + 1 #count += 1

輸出：

解釋：

while條件爲真（True永遠爲真），代碼塊就一直執行（程序無限執行）。（程序中count +=1與count = count + 1是等價的）。

加入while條件循環的猜數字：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:Mclind

age = 56

while True:
    guess_age = int(input("guess age:"))
    if guess_age == age:
        print("yes, you got it.")
    elif guess_age > age:
        print("think smaller...")
    else:
        print("think bigger...")

輸出：

guess age:56

yes, you got it.

guess age:23

think bigger...

解釋：

不管猜對錯，程序無限執行，很差，改進一下：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:Mclind

age = 56

while True:
    guess_age = int(input("guess age:"))
    if guess_age == age:
        print("yes, you got it.")
        break
    elif guess_age > age:
        print("think smaller...")
    else:
        print("think bigger...")

輸出：

guess age:67

think smaller...

guess age:56

yes, you got it.

Process finished with exit code 0

解釋：

break：退出，結束循環。

此時程序猜對退出執行，但猜錯的話仍是無限猜下去，仍是很差，再改進：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:Mclind

age = 56

count = 0

while True:
    if count == 3:
        break
    guess_age = int(input("guess age:"))
    if guess_age == age:
        print("yes, you got it.")
        break
    elif guess_age > age:
        print("think smaller...")
    else:
        print("think bigger...")

    count += 1

輸出：

guess age:1

think bigger...

guess age:2

think bigger...

guess age:3

think bigger...

Process finished with exit code 0

解釋：

程序猜對，或者猜錯三次結束執行，可是仍是很low：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:Mclind

age = 56

count = 0

while count < 3:
    guess_age = int(input("guess age:"))
    if guess_age == age:
        print("yes, you got it.")
        break
    elif guess_age > age:
        print("think smaller...")
    else:
        print("think bigger...")

    count += 1