python基礎(chǔ)1

2019-11-06 06:09:06

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pycharm快捷鍵ctrl+d 復(fù)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(dòng)行ctrl+alt+L 美化代碼tab 補(bǔ)全命令在終端中執(zhí)行py文件:python g:/test.py 1. 變量name = "liming"age = 25PRint(name, "'age is ", age) #print()用來(lái)打印, ,用來(lái)連接name,age="zhangsan",232. 常量全部大寫(xiě)NAME='miling'MySQL_CONNECTION=""3. name = 'Alex'name2 = namename = 'longmingwang' print(name, name2)#longmingwang Alex4. 在pycharm中文件->設(shè)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(huì)有這行注釋5. 在python2中input:輸入的數(shù)字就是數(shù)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(wú)效1 >>> import getpass2 >>> p=getpass.getpass('input your passWord')#輸入密碼時(shí)用getpass代替了input3 input your password4 >>> print(p)5 aaa9. os:在python中執(zhí)行系統(tǒng)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(shù)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(hù)名都沒(méi)蒙對(duì),滾粗!")優(yōu)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(gè)循環(huán) elif guessnum>age: print("elder than age") else: print("smaller than age")13. 程序執(zhí)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(jié)果:n=8n>1end14. 字符串格式化輸出name="liming"print("I am %s" % name)萬(wàn)惡的+:開(kāi)辟多個(gè)內(nèi)存空間print("my name is "+name+"!")15.列表====數(shù)組age=9name=["minglong","minghu","mingchong",3,age]列表名[索引]print(name[0]) #"minglong"print(name[-1]) #age只會(huì)從左到右取: name[0:2] #["minglong","minghu"]name[-3:-1]name[:6]#前五個(gè)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(gè)為minggou的項(xiàng)name.pop(7) #不加參數(shù)默認(rèn)為-1del #刪除內(nèi)存中的數(shù)據(jù),全局使用del student[4:6] #刪除第4,5del student #刪除列表步長(zhǎng):student[0:8:2]個(gè)數(shù):student.count("s2")查找值:判斷是否存在: "s2" in studentstudent.index("s2")#找到的第一個(gè)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(kuò)展:student1.extend(student2)反轉(zhuǎn):動(dòng)作,無(wú)返回值student.reverse()排序:student.sort()#python3中字符串和數(shù)字不能一塊排序復(fù)制:copy:淺層復(fù)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(jié)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(fù)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(jié)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(zhǎng)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(méi)變,得到個(gè)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(shù)字組成,True'fe'.isalpha()----是不是字母'feAFE'.isupper()----是不是全是大寫(xiě)'fwef'.islower()----是不是全是小寫(xiě)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(yàn)證碼:import randomyanzhengma=[]for i in range(6):jj=random.randrange(0,2)if jj==0:#數(shù)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(shù)據(jù)運(yùn)算% -----除法的余數(shù),判斷正奇數(shù)// -----商的整數(shù)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(yùn)算:計(jì)算機(jī)中能存儲(chǔ),表示的最小單位,是一個(gè)二進(jìn)制位byte(字節(jié))=8bit1kbyte=1024byte1Mbyte=1024kbyte1Gbyte=1024Mbyte1 1 1 0 1 1=600 0 1 1 0 1=1360 & 13 =12 ---按位與運(yùn)算60 | 13 =61 ---按位或運(yùn)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(huán)while Truei = 0while True:i += 1if i>50 and i<60:continueprint("i=", i)if i==100:print("fuck!!!")break20.字典{}:無(wú)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(huán)for key in d:print(key) print(d[key]) 取值不抱錯(cuò): d[]可能會(huì)報(bào)錯(cuò)setdefault:存在時(shí)就直接取出(相當(dāng)于get),沒(méi)有就設(shè)置默認(rèn)值后取出print(d.setdefault("003",{"name":"sim"}))get: d.get("003")刪除:d.pop(key)d.popitem() -->隨機(jī)刪除21. 退出程序exit("sorry")打印出列表中索引號(hào):for i in enumerate(range(5)):print(i)結(jié)果為:(0, 0)(1, 1)(2, 2)(3, 3)(4, 4)22.set集合---無(wú)序,不可重復(fù)創(chuàng)建:s={123,456,789,852,46}s=set([])#調(diào)用了構(gòu)造函數(shù)__init__添加元素:add:s.add(123)update:列表或元組或字符串;for循環(huán)加入s.update([1,2,3])#一次添加多個(gè)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(shí)會(huì)報(bào)錯(cuò)discard:s.discard(123)#即使不存在也不會(huì)報(bào)錯(cuò)pop:s.pop() #隨機(jī)刪除,不建議使用交集:s.intersection(s1)s.intersection_update(s1)并集:s.union(s1)23.函數(shù),在py文件中可直接定義,不需要一定在class中定義,參數(shù)傳的是引用默認(rèn)參數(shù): def fun1(x,y,z='ok'): print (x,y,z) return x+y #沒(méi)有return時(shí)默認(rèn)是none print() #不會(huì)被執(zhí)行調(diào)用:fun1(2,3,'ss') #2 3 'ss' fun1(2,3) #2,3,'ok' 動(dòng)態(tài)參數(shù): *args,將傳進(jìn)來(lái)的參數(shù)放在一個(gè)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(huán)的放進(jìn)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(jìn)來(lái)的參數(shù)放在字典中 def ff(**args): print(args,type(args)) 參數(shù):變量='' ff(name="liming",age=21) #args={'name': 'liming', 'age': 21} <class 'dict'> 參數(shù):**{字典} ff(**{'name':"liming"}) #args={'name':'liming'} <class 'dict'> 萬(wàn)能參數(shù): def f(*args,**args): f(1,2,3,name='zhangsan',age=21) 字符串有個(gè)函數(shù):format(*args,**args) 全局變量:大寫(xiě) 任何作用域都能訪問(wèn) 修改全局變量,先:聲明global 變量名再:變量名='' python是面向函數(shù)編程.封裝到函數(shù), 內(nèi)置函數(shù): abs:絕對(duì)值 bool():0,None,False,"",(),[],{}為False all():全為T(mén)rue,才為T(mén)rue,如all([1,2,None])為假 any():有一個(gè)True,就為T(mén)rue,如any([1,2,None])為真 bin():二進(jìn)制0b oct():八進(jìn)制0o hex():十六進(jìn)制0x utf-8:一個(gè)漢字三個(gè)字節(jié),一個(gè)字母一個(gè)字節(jié) gbk:一個(gè)漢字兩個(gè)字節(jié),一個(gè)字母一個(gè)字節(jié) bytes():轉(zhuǎn)化為字節(jié),如bytes('lisa啊',encoding='utf-8')-->b'lisa/xe5/x95/x8a' ,a-z不變,0-9不變,漢字會(huì)轉(zhuǎn)化為3個(gè)字節(jié),每個(gè)字節(jié)為兩個(gè)十六進(jìn)制 str():str(b'lisa/xe5/x95/x8a',encoding='utf-8')-->'lisa啊' .字節(jié)轉(zhuǎn)化為字符串操作文件打開(kāi)文件:f=open('db','r',[encoding='utf-8']) #只讀,讀的是字符串,亂碼時(shí)要寫(xiě)對(duì)encoding f=open('db','rb') #以二進(jìn)制讀取, f=open('db','w') #只寫(xiě),先清空 f=open('db','wb') #以二進(jìn)制寫(xiě)入,f.write(bytes('lisa',encoding='utf-8')) f=open('db','x') #文件存在則報(bào)錯(cuò),不存在,則創(chuàng)建并寫(xiě)內(nèi)容 f=open('db','a') #追加,可讀,不存在則創(chuàng)建,存在則只追加內(nèi)容 +:可以同時(shí)讀寫(xiě):f.seek(1) #按字節(jié)調(diào)整讀指針,跳過(guò)一個(gè)字節(jié),有漢字(三個(gè)字節(jié))會(huì)亂碼)f.tell() #獲取現(xiàn)在指針位置,一個(gè)漢字為三個(gè)字節(jié) f=open('db','r+') #讀寫(xiě),可讀可寫(xiě),因?yàn)樽x導(dǎo)致指針移到最后了,所以write在末尾(追加) f=open('db','w+') #寫(xiě)讀,可讀可寫(xiě) f=open('db','x+') #寫(xiě)讀,可讀可寫(xiě) f=open('db','a+') #寫(xiě)讀,可讀可寫(xiě)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(dòng),無(wú)參數(shù)讀全部,有參數(shù)時(shí)看打開(kāi)方式:r:按字符讀,rb:按字節(jié)讀write():寫(xiě)入,wb時(shí)寫(xiě)入字節(jié)flush():將修改flush到磁盤(pán)readable():w模式打開(kāi)時(shí)Falsereadline():讀取一行,指針隨著一行truncate():截?cái)辔募?指針后清空f(shuō)or line in f:一行一行的讀取文件關(guān)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(lái)執(zhí)行代碼s="print(4)"r=compile(s,'<string>','exec')exec(r)exec:執(zhí)行python代碼,沒(méi)有返回值,接收代碼或字符串exec("print(23)")--->23eval:執(zhí)行表達(dá)式運(yùn)算,并返回值eval("print(23)")--->23,并返回Noneeval('8*8') ---->返回64dir:查看對(duì)象提供了什么功能divmod:得到商和余數(shù),返回元組(商,余數(shù))isinstance:判斷對(duì)象是不是類(lèi)的實(shí)例l=[]r=isinstance(l,dict)print(r) -->False類(lèi):str,dict,liststr的實(shí)例:"alex"dict的實(shí)例:{}list的實(shí)例:[]24. import import math:math是.py文件,里面有def函數(shù)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(zhuǎn)換

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