python基礎1

2019-11-06 06:09:06

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pycharm快捷鍵ctrl+d 復制行ctrl+x 刪除行ctrl+/ 注釋''' 多行注釋,只能用于模塊頭部shift+↑或↓ 選擇shift+alt+↑或↓ 移動行ctrl+alt+L 美化代碼tab 補全命令在終端中執行py文件:python g:/test.py 1. 變量name = "liming"age = 25PRint(name, "'age is ", age) #print()用來打印, ,用來連接name,age="zhangsan",232. 常量全部大寫NAME='miling'MySQL_CONNECTION=""3. name = 'Alex'name2 = namename = 'longmingwang' print(name, name2)#longmingwang Alex4. 在pycharm中文件->設置->editor->文件和代碼模版中修改python script中添加#author xinwang這樣所有的新建python文件都會有這行注釋5. 在python2中input:輸入的數字就是數字,"alex"是文本,alex是變量raw_input:輸入全部是文本在python3中input:輸入的全是文本6. '''打印多行文本7. 例子name = input("please input your name:")age = int(input("please input your age:"))job = input("please input your job:")msg = ('''information of user %s---------------------------name : %sage : %djob : %s''') % (name, name, age, job)print(msg)8. getpass:在pycharm中無效1 >>> import getpass2 >>> p=getpass.getpass('input your passWord')#輸入密碼時用getpass代替了input3 input your password4 >>> print(p)5 aaa9. os:在python中執行系統命令import osprint(os.system("top"))os.mkdir("/home/wangxin/test)print(os.system("ls -l /"))保存命令輸出:rs=os.popen("df").read()print(rs)10.sysimport sysprint(sys.argv) #參數print(sys.path)11. if ... else模擬登錄:user = 'alex'passd = 'alex'username = input("username:")password = input("password:")if username == user:print("the username is correct...")if password==passd:print ("welcome to login")else:print("but your password is invalid")else:print("連用戶名都沒蒙對,滾粗!")優化:if username == user and passd==password:print("welcome to login")else:print("your username or password is invalid!")age=21guessnum=int(input("guess age:"))if age==guessnum :print("got it! so smart!")elif guessnum>age:print("elder than age")else:print("smaller than age")12. for i in 列表:age=21for i in range(10): #range(10)=[0,1,2,3,4,5,6,7,8,9] guessnum=int(input("guess age:")) if age==guessnum : print("got it! so smart!") break #不往后走了,跳出整個循環 elif guessnum>age: print("elder than age") else: print("smaller than age")13. 程序執行順序n = int(input("n="))if n > 1:print("n>1")elif n > 2:print("n>2")else:print("heha")print("end")結果:n=8n>1end14. 字符串格式化輸出name="liming"print("I am %s" % name)萬惡的+:開辟多個內存空間print("my name is "+name+"!")15.列表====數組age=9name=["minglong","minghu","mingchong",3,age]列表名[索引]print(name[0]) #"minglong"print(name[-1]) #age只會從左到右取: name[0:2] #["minglong","minghu"]name[-3:-1]name[:6]#前五個name[:]全部name[2:6][2:4][0][1]賦值name[1]="newname"name.insert(2,"minggou")#在2元素前插入name.append("alex")#在列表最后插入刪除:name.remove("minggou")#刪除找到的第一個為minggou的項name.pop(7) #不加參數默認為-1del #刪除內存中的數據,全局使用del student[4:6] #刪除第4,5del student #刪除列表步長:student[0:8:2]個數:student.count("s2")查找值:判斷是否存在: "s2" in studentstudent.index("s2")#找到的第一個s2的索引位置eg:改掉里面所有的s4:for i in range(student.count('s4')):i=student.index("s4")student[i]="444"清空:student.clear()擴展:student1.extend(student2)反轉:動作,無返回值student.reverse()排序:student.sort()#python3中字符串和數字不能一塊排序復制:copy:淺層復制student2=student.copy()eg:student = [1, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12]student2 = student.copy()student[0] = 54print(student)print(student2)student[4][0]=64365464print(student)print(student2)結果為:[54, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12][1, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12][54, 2, 3, 4, [64365464, 7, 6, 5], 43, 32, 12][1, 2, 3, 4, [64365464, 7, 6, 5], 43, 32, 12]deepcopy:深層復制import copystudent2=copy.deepcopy(student)eg:import copystudent = [1, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12]student2 = student.copy()student3 = copy.deepcopy(student)student[0] = 54print(student)print(student2)print(student3)student[4][0]=64365464print(student)print(student2)print(student3)結果:[54, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12][1, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12][1, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12][54, 2, 3, 4, [64365464, 7, 6, 5], 43, 32, 12][1, 2, 3, 4, [64365464, 7, 6, 5], 43, 32, 12][1, 2, 3, 4, [5, 7, 6, 5], 43, 32, 12]長度:len(student)16.元組:不可修改( )tuple17.字符串str.strip() ---刪除兩邊空白-空格,tabstr.split() ---str沒變,得到個列表"|".join(['a','bc','1']) ---將列表中元素(必須都是字符串)用|拼成字符串 :a|bc|1"".join(['a','b','c'])-->abc"" in "alex li" ----判斷空格"1234".isdigit()----判斷字符串是否是純數字組成,True'fe'.isalpha()----是不是字母'feAFE'.isupper()----是不是全是大寫'fwef'.islower()----是不是全是小寫ord('c') -->99chr(99) -->c格式化:formatmsg = "name={0},age={1}"print(msg.format('liming', 27))"alex".center(40,"-") #------------------alex------------------"alex".find("ex")#2,返回所引print("abcd".endswith("d")) #Trueprint("abcd".startswith("a"))#True字符串是列表:for i in 'abcd':print(i)eg:生成六位驗證碼:import randomyanzhengma=[]for i in range(6):jj=random.randrange(0,2)if jj==0:#數字temp=random.randrange(0,10)yanzhengma.append(str(temp))else:temp=random.randrange(65,91)r=chr(temp)yanzhengma.append(r)yanzhengma="".join(yanzhengma)print(yanzhengma)18. 數據運算% -----除法的余數,判斷正奇數// -----商的整數部分!= -----不等于== -----等于賦值:左邊一定是變量 = -----賦值 += -----相加;c+=a-->c=a+c -=andornot位運算:計算機中能存儲,表示的最小單位,是一個二進制位byte(字節)=8bit1kbyte=1024byte1Mbyte=1024kbyte1Gbyte=1024Mbyte1 1 1 0 1 1=600 0 1 1 0 1=1360 & 13 =12 ---按位與運算60 | 13 =61 ---按位或運算60 ^ 13=49 ---按位異或~60=195-256=-61 ---按位取反 64<<1=128 左移1位64>>1=32 右移1位19.死循環while Truei = 0while True:i += 1if i>50 and i<60:continueprint("i=", i)if i==100:print("fuck!!!")break20.字典{}:無序d={key1:value1,key2:value2,key3:value3}d[key2]=value_2_neweg:d = {"001": {"name": "liming","age": 25,"address": "henan"},"002": {"name": "zhangsan","age": 65,"address": "yongxia"},"003": {"name":"lisi","age":85,"address":"jinan"}}d["002"].pop("age") --->刪除age:65print (d["002"]["age"])取出所有的keys列表d.keys() 取出所有的values列表d.values()判斷key是否存在"003" in d ---->True循環for key in d:print(key) print(d[key]) 取值不抱錯: d[]可能會報錯setdefault:存在時就直接取出(相當于get),沒有就設置默認值后取出print(d.setdefault("003",{"name":"sim"}))get: d.get("003")刪除:d.pop(key)d.popitem() -->隨機刪除21. 退出程序exit("sorry")打印出列表中索引號:for i in enumerate(range(5)):print(i)結果為:(0, 0)(1, 1)(2, 2)(3, 3)(4, 4)22.set集合---無序,不可重復創建:s={123,456,789,852,46}s=set([])#調用了構造函數__init__添加元素:add:s.add(123)update:列表或元組或字符串;for循環加入s.update([1,2,3])#一次添加多個元素s.update("abcdabcd")#新增了'a','b','c','d'清空:s.clear()差異:s.different(s1)#s中存在,s1中不存在s1.symmetric_difference(s)#并集中去掉交集差異更新:s.different(s1)#求差異更新到s中s1.symmetric_difference_update(s)移除:remove:s.remove(111)#不存在時會報錯discard:s.discard(123)#即使不存在也不會報錯pop:s.pop() #隨機刪除,不建議使用交集:s.intersection(s1)s.intersection_update(s1)并集:s.union(s1)23.函數,在py文件中可直接定義,不需要一定在class中定義,參數傳的是引用默認參數: def fun1(x,y,z='ok'): print (x,y,z) return x+y #沒有return時默認是none print() #不會被執行調用:fun1(2,3,'ss') #2 3 'ss' fun1(2,3) #2,3,'ok' 動態參數: *args,將傳進來的參數放在一個元祖中 eg: def ff(*args): print(args) ff("nilian","hello","world") #args=('nilian', 'hello', 'world') ff(("nilian","hello","world")) #args=(('nilian', 'hello', 'world')) ff(["nilian","hello","world"]) #args=(['nilian', 'hello', 'world']) 循環的放進元祖中: ff(*"hello") #args=('h', 'e', 'l', 'l', 'o') <class 'tuple'> ff(*("hello","world")) #args=('hello', 'world') <class 'tuple'> ff(*["hello","world"]) #args=('hello', 'world') <class 'tuple'> **args:將傳進來的參數放在字典中 def ff(**args): print(args,type(args)) 參數:變量='' ff(name="liming",age=21) #args={'name': 'liming', 'age': 21} <class 'dict'> 參數:**{字典} ff(**{'name':"liming"}) #args={'name':'liming'} <class 'dict'> 萬能參數: def f(*args,**args): f(1,2,3,name='zhangsan',age=21) 字符串有個函數:format(*args,**args) 全局變量:大寫任何作用域都能訪問修改全局變量,先:聲明global 變量名再:變量名='' python是面向函數編程.封裝到函數, 內置函數: abs:絕對值 bool():0,None,False,"",(),[],{}為False all():全為True,才為True,如all([1,2,None])為假 any():有一個True,就為True,如any([1,2,None])為真 bin():二進制0b oct():八進制0o hex():十六進制0x utf-8:一個漢字三個字節,一個字母一個字節 gbk:一個漢字兩個字節,一個字母一個字節 bytes():轉化為字節,如bytes('lisa啊',encoding='utf-8')-->b'lisa/xe5/x95/x8a' ,a-z不變,0-9不變,漢字會轉化為3個字節,每個字節為兩個十六進制 str():str(b'lisa/xe5/x95/x8a',encoding='utf-8')-->'lisa啊' .字節轉化為字符串操作文件打開文件:f=open('db','r',[encoding='utf-8']) #只讀,讀的是字符串,亂碼時要寫對encoding f=open('db','rb') #以二進制讀取, f=open('db','w') #只寫,先清空 f=open('db','wb') #以二進制寫入,f.write(bytes('lisa',encoding='utf-8')) f=open('db','x') #文件存在則報錯,不存在,則創建并寫內容 f=open('db','a') #追加,可讀,不存在則創建,存在則只追加內容 +:可以同時讀寫:f.seek(1) #按字節調整讀指針,跳過一個字節,有漢字(三個字節)會亂碼)f.tell() #獲取現在指針位置,一個漢字為三個字節 f=open('db','r+') #讀寫,可讀可寫,因為讀導致指針移到最后了,所以write在末尾(追加) f=open('db','w+') #寫讀,可讀可寫 f=open('db','x+') #寫讀,可讀可寫 f=open('db','a+') #寫讀,可讀可寫eg:f=open('db','r+',encoding='utf-8')r=f.read(1) #漢字print(r)p=f.tell() #3f.seek(p)f.write('lisi|35252')f.close()操作文件:f.read():讀取,指針隨著移動,無參數讀全部,有參數時看打開方式:r:按字符讀,rb:按字節讀write():寫入,wb時寫入字節flush():將修改flush到磁盤readable():w模式打開時Falsereadline():讀取一行,指針隨著一行truncate():截斷文件,指針后清空for line in f:一行一行的讀取文件關閉文件:f.close() with open('db','r') as f,open('db1','r') as f2:passpasscompile:將字符串編譯成python代碼,eval,exec來執行代碼s="print(4)"r=compile(s,'<string>','exec')exec(r)exec:執行python代碼,沒有返回值,接收代碼或字符串exec("print(23)")--->23eval:執行表達式運算,并返回值eval("print(23)")--->23,并返回Noneeval('8*8') ---->返回64dir:查看對象提供了什么功能divmod:得到商和余數,返回元組(商,余數)isinstance:判斷對象是不是類的實例l=[]r=isinstance(l,dict)print(r) -->False類:str,dict,liststr的實例:"alex"dict的實例:{}list的實例:[]24. import import math:math是.py文件,里面有def函數例如sqrt,還有class from math import sqrt:從math文件中引入def sqrt.25.ascii和字符轉換

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