CS50P 1_Condition

Conditions 條件判斷

「如果 ... 就 ... 否則 ... 」

conditional statement (判斷式)

「如果室內溫度超過 28 度時，就啟動冷氣運作。」

「如果感測器所偵測的數值大於 60 時，
就點亮紅色警示燈，否則點亮綠色警示燈。」

流程圖符號

if else statement

if condition:
    do condition True things
    .
    .
    .

Indentation 縮排

if statement 沒有縮排

score = int(input("請輸入分數"))
if score >= 60: #如果分數大於等於60 則成績及格:)    
print("成績及格 :)")

if statement exanmple 成績及格

score = int(input("請輸入分數"))
if score >= 60: #如果分數大於等於60 則成績及格:)    
    print("成績及格 :)")

請輸入分數 100
成績及格 :)

if else statement

if condirtion:
    do condition True things
    .
    .
    .
else:
    do condition False things
    .
    .
    .

if else example 成績及格

score = int(input("請輸入分數"))
if score >= 60: #如果分數大於等於60 則成績及格:) 
    print("成績及格:)")
else:           #否則分數小於60 成績不及格!! 
    print("成績不及格!!")

請輸入分數 100
成績及格:)

請輸入分數 50
成績不及格!!

Two if example 成績及格

score = int(input("請輸入分數"))
if score >= 60: #如果分數大於等於60 則成績及格:)
    print("成績及格:)")
if score < 60:  #如果分數小於60 則成績不及格!!
    print("成績不及格!!")

請輸入分數 100
成績及格:)

請輸入分數 50
成績不及格!!

If-Else Running

Two If Running

If-elif-else Multiple Conditions

if condirtion_1:
    do condition_1 True things
    ...
elif condition_2: 
    do condition_2 False things
    ...
.
.
.
elif condition_n:
     do condition_n False things
    ...
else:
    do all conditions False things
    ...

成績等第判斷 I

and : 且

score = int(input("score: "))
if 90 <= score and score <= 100:
    print('Grade is: A')
elif 80 <= score and score < 90:
    print('Grade is: B')
elif 70 <= score and score < 80:
    print('Grade is: C')
elif 60 <= score and score < 70:
    print('Grade is: D')
else:
    print('Grade is: F')

score: 100
Grade is: A

成績等第判斷 II

score = int(input("score: "))
if 90 <= score <= 100:
    print('Grade is: A')
elif 80 <= score < 90:
    print('Grade is: B')
elif 70 <= score < 80:
    print('Grade is: C')
elif 60 <= score < 70:
    print('Grade is: D')
else:
    print('Grade is: F')

score: 100
Grade is: A

成績等第判斷 III

score = int(input("score: "))
if score >= 90:
    print('Grade is: A')
elif score >= 80:
    print('Grade is: B')
elif score >= 70:
    print('Grade is: C')
elif score >= 60:
    print('Grade is: D')
else:
    print('Grade is: F')

score:  60
Grade is: D

String Comparison

answer = input("Do you agree? ")
if answer == 'yes':
  print("Agreed")
else:
  print("Not Agreed")

answer = input("Do you agree? ").strip().lower()
if answer == 'yes':
  print("Agreed")
else:
  print("Not Agreed")

String compare

answer = input("Do you agree? ").strip().lower()
if answer == 'yes' or answer == 'y'
  print("Agreed")
else:
  print("Not Agreed")

String Compare

day = input("今天星期幾呢？")
if day == "Monday":
    print("新的星期，加油！")
elif day == "Tuesday": 
    print("這禮拜你將完成很多事情！")
elif day == "Wednesday": 
    print("第三天，好好發揮工作精神！")
elif day == "Thursday": 
    print("你已經撐過一半了！")
elif day == "Friday":
    print("再撐一天就好了！") 
elif day == "Saturday":
    print("假期愉快 ^.^")
elif day == "Sunday":
    print("把握假期的最後一天！")
else:
    print("你是不是輸入錯誤了呢？")

今天星期幾呢？ Friday
再撐一天就好了！
今天星期幾呢？ 1
你是不是輸入錯誤了呢？

Using match with case after Python 3.10

name = input("What's your name? ")

match name:
    case "Harry":
        print("Gryffindor")
    case "Hermione":
        print("Gryffindor")
    case "Ron":
        print("Gryffindor")
    case "Draco":
        print("Slytherin")
    case _:
        print("Who?")

What's your name? Harry
Gryffindor

Practice: Determine if a Number is a Multiple of 7 🤔

讓使用者輸入一個數字，判斷它是不是7的倍數

Hint : 數字除以7，如果能整除，就是7的倍數 x % 7 == 0， x 就是7的倍數

% 求餘數 ==> X % Y 求 X 除以 Y 的餘數