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2017 iT 邦幫忙鐵人賽
DAY 5
1
自我挑戰組

Python 學習筆記系列 第 5

Day5 Python 基礎 - while流程判斷

接續上次的代碼,是不是只有執行一次才就結束,想要再繼續猜,就要在執行一次,是不是有點挺麻煩的?
所以這次我們就來再多做一點點功能進去,讓代碼可以多次循環地執行代碼,Go....

首先,我們先來了解一下,簡單的 while循環 怎麼寫

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

count = 0

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

---------------執行結果---------------

count: 70937
count: 70938
count: 70939
count: 70940
count: 70941
count: 70942
count: 70943
count: 70944

上面的代碼是一個簡單的 while循環 ,這是一個無限的迴圈,只要while為真,就會一直執行不會中斷,需要由使用者自行中斷,簡單的會了,我們開始來結合上次的代碼

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

age_of_ironman = 35

while True:
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")

---------------執行結果---------------

guess age:23
You may think bigger...
guess age:98
You may think smaller...
guess age:84
You may think smaller...
guess age:35
Bingo, You got it!!!
guess age:

咦~有發現什麼不尋常的地方嗎?沒錯,即使你輸入正確了,這遊戲也不會結束,所以我們要在新增一個可以結束遊戲的條件
要怎麼結束呢? 這時候必須在代碼中加入 break 就可以了,再修改一下代碼

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

age_of_ironman = 35

while True:
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
        break
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")

---------------執行結果---------------

guess age:39
You may think smaller...
guess age:28
You may think bigger...
guess age:59
You may think smaller...
guess age:39
You may think smaller...
guess age:35
Bingo, You got it!!!

Process finished with exit code 0

這樣又達成目的了,可是瑞凡,人家想要限制遊戲猜只能猜三次,三次猜不中就退出遊戲,又該怎麼寫呢?這時候就需要一個計數器來協助完成這次的任務,所以再為代碼稍稍加強一下功能

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

age_of_ironman = 35

count = 0

while True:
    if count >= 3:
        break
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
        break
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")
    count += 1

---------------執行結果---------------

# 故意猜超過三次,看看結果
guess age:1
You may think bigger...
guess age:1
You may think bigger...
guess age:1
You may think bigger...

Process finished with exit code 0


# 先試試在三次內打對密碼,看看結果
guess age:3
You may think bigger...
guess age:36
You may think smaller...
guess age:35
Bingo, You got it!!!

Process finished with exit code 0

hmm...上面代碼我們透過 count 這個計數器成功達成條件了,接下來要來想想,怎麼優化這個代碼?

上面代碼是不是可以把 if count >= 3: 放進 while 裡,修改一下代碼

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

age_of_ironman = 35

count = 0

while count <= 3:
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
        break
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")
    count += 1

---------------執行結果---------------

# 故意猜超過三次,看看結果
guess age:1
You may think bigger...
guess age:69
You may think smaller...
guess age:34
You may think bigger...

Process finished with exit code 0

# 先試試在三次內打對密碼,看看結果
guess age:32
You may think bigger...
guess age:35
Bingo, You got it!!!

Process finished with exit code 0

while count < 3 就會變成有條件的,當count 小於 3就執行,如果大於3,就不執行。

但還是有稍微美中不足的地方,就是輸入超過三次,並沒有打印出任何訊息,會讓人感覺有點莫名其妙,所以再修改一下代碼

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

age_of_ironman = 35

count = 0

while count <= 3:
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
        break
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")
    count += 1

print("You have tried too many, exit")

---------------執行結果---------------
# 故意猜超過三次,看看結果
guess age:3
You may think bigger...
guess age:3
You may think bigger...
guess age:3
You may think bigger...
You have tried too many, exit

Process finished with exit code 0

# 先試試在三次內打對密碼,看看結果
guess age:4
You may think bigger...
guess age:35
Bingo, You got it!!!
You have tried too many, exit

Process finished with exit code 0

咦~怎麼打對密碼也顯示 You have tried too many, exit,看來還做得不夠好,再修改一下代碼

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

age_of_ironman = 35

count = 0

while count <= 3:
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
        break
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")
    count += 1

if count == 3:
    print("You have tried too many, exit")

---------------執行結果---------------
# 故意猜超過三次,看看結果
guess age:1
You may think bigger...
guess age:2
You may think bigger...
guess age:3
You may think bigger...
You have tried too many, exit

Process finished with exit code 0

# 先試試在三次內打對密碼,看看結果
guess age:15
You may think bigger...
guess age:35
Bingo, You got it!!!

Process finished with exit code 0

呼,這次終於都對了…
可是我們還有另一種更牛逼的寫法,是 Python 特有的寫法
就讓我們最後一次修改代碼,讓它看起來更牛逼點!!!

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

age_of_ironman = 35

count = 0

while count <= 3:
    guess_age = int(input("guess age:"))
    if guess_age == age_of_ironman:
        print("Bingo, You got it!!!")
        break
    elif guess_age > age_of_ironman:
        print("You may think smaller...")
    else:
        print("You may think bigger...")
    count += 1
else:
    print("You have tried too many, exit")

---------------執行結果---------------
# 故意猜超過三次,看看結果
guess age:4
You may think bigger...
guess age:5
You may think bigger...
guess age:6
You may think bigger...
You have tried too many, exit

Process finished with exit code 0


# 先試試在三次內打對密碼,看看結果
guess age:7
You may think bigger...
guess age:67
You may think smaller...
guess age:35
Bingo, You got it!!!

Process finished with exit code 0

終於完成了,但這個是怎麼判斷的呢?請看下圖

倒數25天,繼續加油了…


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Day4 Python 基礎 - if-else流程判斷
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Day6 Python 基礎 - for流程判斷
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