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Strings, tuples, and dictionaries 1, String A string is an immutable sequence of several different unicode characters 1 . String creation #Single quote string str1 = 'It's going to rain. My mother wants to get married. Let him go' str2 = str() #Empty string str3 = str([10,20,30]) #Double quoted string str2 = "It's going to rain. My mother ...

brief introduction This article summarizes and briefly introduces the logs in mysql, which will not be involved too deeply. The main purpose is to have a systematic understanding of the log files in MySQL. Each log file will be specifically analyzed and summarized later. Log classification Log files in MySQL include configuration files, erro ...

Long format dataframe and wide format dataframe are two forms of data frames, which appear frequently in data analysis. In the process of data processing, It is often necessary to switch between the two. Based on pandas, this paper introduces the mutual conversion operation of long data and wide data. environment python3.9win10 64bitpandas= ...

brief introduction This article summarizes and briefly introduces the logs in mysql, which will not be involved too deeply. The main purpose is to have a systematic understanding of the log files in MySQL. Each log file will be specifically analyzed and summarized later. Log classification Log files in MySQL include configuration files, error ...

Since the videos in Silicon Valley are made by Eclipse software, some of which are different from IDEA, I'm here to share with you the differences between IDEA and Eclipse's operation, the source code involved in the operation (slightly different from the source code of the video), and the various problems you may encounter. These sources are t ...

Set 41: The function of a function fun in a given program is to calculate the average of N numbers in the array indicated by x (specifying that all numbers are positive), return the main function by a parameter, return the number that is less than the average and closest to the average as the function value, and output it in the main function. ...

preface object-oriented It is a very common programming idea. Through a practical project, this paper will take you into object-oriented and experience the application of object-oriented in practical development, which brings us convenience. The project of this paper comes from Dark horse programmer An example in a series of courses. Th ...

Recently, there are some offline breakpoint download requirements involved in the process of doing the project, and the two objects of NSURLConnection and NSRULSession are used. Most of the working time is dealing with AFNetworking, so they are not so proficient in using these two objects. Therefore, I want to sort them out today for future vie ...

Characteristic Fully using Shiro's annotated configuration to maintain high flexibility. Give up cookies, Session, and use JWT for authentication to fully implement stateless authentication. JWT keys support expiration times. Provides support across domains. Dead work Before starting this tutorial, make sure you are familiar with the followin ...

java Source Analysis-Compile-Time Annotation Processor In the previous article, we took a general look at how runtime annotation processors work. In this film, we discuss the underlying implementation of compile-time annotation processors. 1.Annotation Processing Tool 1.1 Overview The Java Compile-Time Annotation Processing Tool (APT) is a ...