from decimal import Decimal  #從decimal 包導(dǎo)入Decimal  類
mydec = Decimal("3.22")   #將字符串轉(zhuǎn)換成decimal類型
print(mydec, type(mydec))
mydec2 = Decimal(3.22)   #浮點(diǎn)型3.22 是不精確的，轉(zhuǎn)換成decimal就是精確的
print(mydec2, type(mydec))

結(jié)果：3.22 <class 'decimal.Decimal'>
3.220000000000000195399252334027551114559173583984375 <class 'decimal.Decimal'>

>>> a = 4 + 5j
>>> a.imag
5.0
>>> a.real
4.0

>>> a=0b11  二進(jìn)制   binary
>>> type(a)  
<class 'int'>  
>>> b=0o11  八進(jìn)制 octonary
>>> type(b)
<class 'int'> 
>>> c=0x11 十六制   hexadecimal
>>> type(c)
<class 'int'> 

>>> num = 100
>>> bin(num)  整型轉(zhuǎn)換成二進(jìn)制，()里面只能是整型
              任意進(jìn)制轉(zhuǎn)2進(jìn)制, 接收一個(gè)int, 返回一個(gè)str
'0b1100100'   
>>> oct(num) 任意進(jìn)制轉(zhuǎn)8進(jìn)制, 接收一個(gè)int, 返回一個(gè)str
'0o144'
>>> hex(num)   任意進(jìn)制轉(zhuǎn)16進(jìn)制, 接收一個(gè)int, 返回一個(gè)str
'0x64'

>>> int (0o11) 接收整型 
9
>>> int("0o11",base=8) 接收整型，但要指定幾進(jìn)制
9
>>> int("11")  接收整型，可以不指定，因?yàn)樗且粋€(gè)數(shù)字
11

>>> a = 'abcdefghijklmnopq'
>>> a[0]
'a'
>>> a[-8]
'j'

str[start:end:step]       左閉右開
step 為正數(shù) 從左至右
step 為負(fù)數(shù) 從右至左
str[2:]  從左至右 第三個(gè)數(shù)開始
str[:7] 從左至右到第七位
str[::-1]  從右至左 步長(zhǎng)為1
str[4::-2]  從第五個(gè)數(shù)開始從右至左 步長(zhǎng)為2

>>> a = 'abcdefghijklmnopq'  一旦定義不可改變
>>> a[2:5]
'cde'

>>> str1="qqq"
>>> str2 = "lll"
>>> str1+str2 # 字符串拼接
'qqqlll'
>>> str3="abc"  
>>> str3*3  
'abcabcabc'字符串復(fù)制
>>> result = str(100)  # int轉(zhuǎn)換成字符串
>>> type(result)
<class 'str'>
>>> result
'100'

>>> str7= "helloabc xx zz"
>>> str7.startswith("abc")
False
>>> str7.startswith("abc",5)
True
>>> str7.startswith("abc",5,7)
False
>>> str7.startswith("abc",5,8)
True

>>> str7
'helloabc xx zz'
>>> str7.upper()  轉(zhuǎn)大寫
'HELLOABC XX ZZ'
>>> str7.title()  轉(zhuǎn)標(biāo)題格式
'Helloabc Xx Zz'
>>> str9 = str7.title().swapcase()  大小寫互換
>>> str9
'hELLOABC xX zZ'
>>> str9 = "a b c d e f"
>>> str9.split()  默認(rèn)按空格切割
['a', 'b', 'c', 'd', 'e', 'f']
>>> str10 = "a#b#c#d#e#f#g#h"
>>> str10.split("#")
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
>>> str11 = str10.split("#")
>>> str11
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
>>> "*".join(str11)
'a*b*c*d*e*f*g*h'

num1 = 0.1416926   #轉(zhuǎn)換成百分位
print("%.2f%% " % (num1 * 100))

print(f"my name is {name}，my age is {age}")
結(jié)果：my name is sc，my age is 4  
print(f"my name is {name}，my age is {age:*>10}")
結(jié)果：my name is sc，my age is *********4

a = "字符串拼接1"
b = "字符串拼接2"
print("方式1：" + a + b)
print("方式2：%s%s" % (a, b))
print(f"方式3：{a}{b}")
print("方式4：{0}{1}".format(a, b))
c = a + b
print("新拼接的字符串長(zhǎng)度為：", len(c))
print("第七個(gè)字符為：", c[6])
str1 = "8*y*cali*china**it*soft*linux*python"
count = str1.count("*")
list = str1.split("*")
str2 = "".join(list)
print("*" * count + str2)

str1 = "8*y*cali*china**it*soft*linux*python"
count = str1.count("*")
list = str1.split("*")
str2 = "".join(list)
print("*" * count + str2)

>>> str1 = "你好" 
>>> str2 = "hejin"
>>> str1+str2    #方式1:加號(hào)拼接
'你好hejin'
>>> "".join([str1,str2])  #方式2:join拼接
'你好hejin'
>>> print("%s,%s"%(str1,str2))  #方式3:% 占位符
你好,hejin
>>> "{},{}".format(str1,str2)   #方式4:format()
'你好,hejin'
>>> "{0},{1}".format(str1,str2) # 方式5 
'你好,hejin'
>>> "{1},{0}".format(str1,str2)
'hejin,你好'
>>> "{a},{b}".format(a=str1,b=str2)  # 方式6 
'你好,hejin'
>>> "{b},{a}".format(a=str1,b=str2)
'hejin,你好'
>>> f"{str1},{str2}"  # 方式7：f格式化
'你好,hejin'

嫌疑人A、B、C、D的筆錄如下，其中三人為真，一人為假：
a:我不是小偷
b:C是小偷
c:小偷肯定是D
d:小偷肯定是D

lst = ["a", "b", "c", "d"]
for x in lst:
    if ("a" != x) + ("c" == x) + ("d" == x) + ("d" != x) == 3:
        print(f"{x}是小偷")