Python 100天-從新手到大師學習筆記Day02：語言元素

jackfrued/Python-100-Days

變數

進行數學計算

a = 321
b = 123
print(a + b)
print(a - b)
print(a * b)
print(a / b)
print(a // b)
print(a % b)
print(a ** b)

使用input()和int()

"""
使用input輸入函數
使用int()轉換成int  #int為整數型態
用占位符號格式化輸出的字串
"""
a = int(input('a = '))
b = int(input('b = '))
print('%d + %d = %d' % (a, b, a + b))
print('%d - %d = %d' % (a, b, a - b))
print('%d * %d = %d' % (a, b, a * b))
print('%d / %d = %f' % (a, b, a / b))
print('%d // %d = %d' % (a, b, a // b))
print('%d %% %d = %d' % (a, b, a % b))
print('%d ** %d = %d' % (a, b, a ** b))

使用type()

"""
使用type()檢查變數的類型
"""
a = 100
b = 12.345
c = 1 + 5j
d = 'hello, world'
e = True
print(type(a))
print(type(b))
print(type(c))
print(type(d))
print(type(e))
int()：將數值或字串轉為整數
float()：將字串轉成浮點數(即有小數點的數字)
str()：轉成字串。(可用於將random模組產生出的數字轉為字串，方便翻頁爬蟲)

運算符號

a = 5
b = 10
c = 3
d = 4
e = 5
a += b            #a=a+b
a -= c            #a=a-c
a *= d            #a=a*d
a /= e            #a=a/e
print("a = ", a)
flag1 = 3 > 2
flag2 = 2 < 1
flag3 = flag1 and flag2
flag4 = flag1 or flag2
flag5 = not flag1
print("flag1 = ", flag1)
print("flag2 = ", flag2)
print("flag3 = ", flag3)
print("flag4 = ", flag4)
print("flag5 = ", flag5)
print(flag1 is True)
print(flag2 is not False)

華氏溫度轉攝氏溫度

f = float(input('輸入華氏溫度: '))
c = (f - 32) / 1.8
print('%.1f華氏度 = %.1f攝氏度' % (f, c))

輸入圓半徑計算周長和面積

import math
radius = float(input('輸入圓的半徑: '))
perimeter = 2 * math.pi * radius
area = math.pi * radius * radius
print('周長: %.2f' % perimeter)
print('面積: %.2f' % area)

判斷年份是否為閏年

year = int(input('輸入年份: '))

is_leap = (year % 4 == 0 and year % 100 != 0 or
           year % 400 == 0)
print(is_leap)
#印出True或者False

字串進階

str1 = 'hello, world!'
print('字串長度:', len(str1))
print('首字母大寫: ', str1.title())
print('字串變大寫: ', str1.upper())
# str1 = str1.upper()
print('字串是不是大寫: ', str1.isupper())
print('字串是不是以hello開頭: ', str1.startswith('hello'))
print('字串是不是以hello結尾: ', str1.endswith('hello'))
print('字串是不是以驚嘆號開頭: ', str1.startswith('!'))
print('字串是不是以驚嘆號結尾: ', str1.endswith('!'))
str2 = '- \u9a86\u660a'
str3 = str1.title() + ' ' + str2.lower()
print(str3)