技術標籤：Python基礎python

刪除變數

name = "alex"
print(name)
del name
print(name)

結果圖

name = "Alex"
name2 = name
print(name)
print(name2)
print(id(name))
print(id(name2))

name = "Jack"
print(name)
print(name2)

name指向Jack
name2指向Alex

資料型別

age_alex = 26
alex_salary = 2000
type
 
(age_alex)
type(alex_salary)
print(type(age_alex) )
print(type(alex_salary) )

字元型

age = 22
age2 = "22"
print(type(age) )
print(type(age2) )#只有是字元才要加引號

float（浮點型）

print(type(2.32))
print(type(-3.14))

字串 在Python中加了引號的字串都被認為是字串

name = "Alex Li"
age = "22"
msg = '''My name is Alex,I am 22'''
 

hometown = 'shandong'

因為有單引號所以需要雙引號

msg = "My name is Alex,I'm 22 "

多引號 多引號的作用就是多行字串必須用多引號

msg = '''
今天我寫首詩
真好
'''
msg = """
今天我寫首詩
真好
"""
print(msg)

大小寫

print(msg.upper())
print(msg.lower())
msg1 = msg.upper()#想要儲存還需要賦值

MY NAME IS ALEX,I AM 22
my name is alex,i am 22

print(name.center(50,"-"))#50是50個位元組

---------------------Alex Li----------------------

字元相加，相乘

name = "alex"
hometown = "usa"
print(name+hometown)
print(name*2)

alexusa
alexalex

列表

names = []
print(type(names))

<class ‘list’>

names = ["Alex","Jack","Rain","wusir","bk"]
print(names)

[‘Alex’, ‘Jack’, ‘Rain’, ‘wusir’, ‘bk’]

names[0]

‘Alex’

names[4]

‘bk’

更改

names = ["Alex","Jack","Rain","wusir","bk"]
names[4] = "黑"
print(names)

[‘Alex’, ‘Jack’, ‘Rain’, ‘wusir’, ‘黑’]

在0，1，2，3，4的4前面插入

names.insert(4,"金角大王")
print(names)

在列表後面

names.append("金大王")#在列表後面
print(names)

[‘Alex’, ‘Jack’, ‘Rain’, ‘wusir’, ‘金角大王’, ‘黑’, ‘金大王’]

刪除4

del names[4]
print(names)

[‘Alex’, ‘Jack’, ‘Rain’, ‘wusir’, ‘黑’, ‘金大王’]

他只是從左向右刪除找刪除一個Alex

names = ["Alex","Jack","Rain","wusir","bk","Alex"]
names.remove("Alex")
print(names)#他只是從左向右刪除找刪除一個Alex

[‘Jack’, ‘Rain’, ‘wusir’, ‘bk’, ‘Alex’]

查詢

"rain" in names#查詢

False

"Rain" in names

True

輸出10行金角大王

a = """
金角大王"""
print(a*10)

在末尾插入Alex

names = ["Alex","Jack","Rain","wusir","me"]
names.append("Alex")
print(names)

[‘Alex’, ‘Jack’, ‘Rain’, ‘wusir’, ‘me’, ‘Alex’]

刪除我的me最後在結尾加上

names.remove("me")
names.append("me")
print(names)

[‘Alex’, ‘Jack’, ‘Rain’, ‘wusir’, ‘Alex’, ‘me’]