codecademy python review

(' A.txt ', ' r ', encoding = ' utf-8 ')Print (F.read ())F.seek (0) #表示将光标的位置移动到开头Print (F.read ())F.seek (1) #表示从第一个字符开始读取Print (F.tell ()) #tell表示以字节显示的F.seek (6,0) #代表从文件开头取6个字节, according to the read mode, if it is readable mode, the character is read, the other reads the byteF.seek (6,1) #以当前光标所在的位置为参照物#seek有3种移动方式0, 1 and 2 must be in B mode, and 0 can be used in text modef = open (' a.txt ', ' RB ')F.seek (0,2) #此时光标一直指向最后F.seek ( -1,2) #倒着切一个字节CP text1 ## # #文件习题2 Import Time3With open

#singleton patterns, such as database objects, are instantiated with the same parameters, and there is no need to duplicate objects, wasting memoryclassMysql:__instance=Nonedef __init__(self,host='127.0.0.1', port='3306'): Self.host=host Self.port=Port @classmethoddefSingleton (cls,*args,**Kwargs):if notCls.__instance: CLS.__instance=cls (*args,**Kwargs)returnCls.__instanceobj1=Mysql () obj2=Mysql ()Print(obj1 isOBJ2)#Falseobj3=Mysql.singleton () Obj4=Mysql.singleton ()Print(obj3 isOBJ4)#True#a

One: The order of the in-stack in the statementSame as other languages (c,c++, etc.) into the stack order is the right end of the first execution into the stack (python3.5), before the python2.7 in the stack order is left firstPython2.7:Python2.7.Ten(default, May at -, the: -:xx) [MSC v. the -bit (AMD64)] on Win32type" Help","Copyright","credits"Or"License" forMore information.>>> ls = [1,2,3]>>>print Ls,ls.reverse () #print先入栈执行, and then reverse the stack execution [1,2,3] None>>>Print ls[3

Foreplay: Understand the next queue queues before you make a custom thread poolThe queue can hold the underlying data type, or it can hold special data types such as classes, objects, etc. fromQueue Import Queueclasst:def __init__ (self,num): Self.num=num def printf (self): print (Self.num,id (self.num))if__name__ = ="__main__": Queue= Queue (0) Num= A queue.put (num) #可以存放基础数据类型t=T (num) queue.put (t) #可以存放对象CLS=T queue.put (CLS) #可以存放类DT= Queue.Get() print (ID (dt), dt,type (DT)) #1385649280

Leetcode1Given an array of integers and a target value, find the two numbers in the array and the target values.You can assume that each input corresponds to only one answer, and that the same element cannot be reused.Example:Given nums = [2, 7, one, all], target = 9 because nums[0] + nums[1] = 2 + 7 = 9 so return [0, 1]The idea at the beginning of this topic is to set two non-repeating pointers, which are returned when the number of two digits is the target value.As follows:Class solution (Obje

The code resides on GitHub: Https://github.com/dachenzi/UserLoginScriptBasic Requirements Let the user enter the user name password Show welcome message after successful authentication Exit the program after a three-time error Upgrade Requirements Can support multiple users login (prompt, through the list to save multiple account information) After the user 3 authentication failed, quit the program, start the program again when attempting to log on, or lock the

Describe The dir () function returns a list of the types of variables, methods, and definitions in the current scope, without parameters; With parameters, returns the properties of the parameter, a list of methods. If the parameter contains method __dir__ (), the method is called. If the parameter does not contain __dir__ (), the method will collect the parameter information to the fullest extent. GrammarDir syntax:Dir ([Object])Parameter description: Object--objec

.insert (1, ' abc ')SortList2.sort ()ReverseList2.reverse ()Delete and return a valueList.pop (1)Append elementList2.extend (' Qweq ')Tuple ()Tuples and lists are similarTuples and strings are not becoming-tuples can store a range of values-tuples are typically used in user-defined functions to safely take a set of worthwhile times, that is, the value of the tuple being used does not change.T= (1,a,)Split of a B c=t tupleCommon methods of dictionaries> Dictionary is the only type of mapping (has

1. {} input is curly braceMycat = {' Size ': ' fat ', ' color ': ' Gray ', ' disposition ': ' Loud '} Key: Valuemycat[' size ' = fat2, 3 Methods of the dictionary:Keys (), values (), items (), the values returned by these methods are not real lists, they cannot be modified, but can be traversed with a for loopFor V in Mycat.values ():Print (v)For I in Mycat.keys ():Print (i)For k,v in Mycat.items ():Print (k ': ' V)3. Check if there is a key-value in the dictionary:' Name ' in Spam.keys ()' Valu