Programmer Think

1,qt Find qt dynamic link library used in the project; The steps are as follows ① Open the windeployqt tool used by the project (qt's own tool); ② Enter the directory where the folder is located; Using the cd command ③ Use the command: windeployqt name Exe (execute the command in the directory where the target folder is located)   ...

preface opencv part about image drawing 1, Draw graphics Opencv4 provides the circle () function for drawing graphics Drawing a circle: prototype of the circle() function void circle(InputOutputArray img, Point center, int radius, const Scalar & color, int thickness = 1, int lineType = LINE_8, int shift = 0) img: need to draw a ...

Problem introduction What is hell The case of nested callback functions in callback functions is called callback hell. Callback hell is an operation that occurs to realize the sequential execution of code. example setTimeout(()=>{ console.log('This is the first step') setTimeout(()=>{ console.log('This is the secon ...

Problem Description: In a chessboard composed of 2^k * 2^k squares, just one square is different from other squares. This square is called a special square, and the chessboard with a special square is called a special chessboard. When k ^ 4 is in different positions on the chessboard, there will be a special case, for example, when k ^ 4 is in ...

1. node introduction and environment installation 1.1 why can JavaScript be executed in a browser There is a JavaScript parsing engine in the browser Different browsers use different JavaScript parsing engines chrome browser = > V8Firefox browser = > odinmonkeySafri browser = > jscoreIE browser = > chakraetc The V8 parsing ...

Today's summary 1, Process control Sequential structure: the code is executed from top to bottom, and the statement is executed only once a day. (default) print('hello') print('word') Branch structure: choose to execute or not execute part of the code according to the conditions (use if) age = 10 if age >= 18: print('adult') else: ...

1, Use of File class 1. Use of file class Use of File class① An object of the File class that represents a File or a File directory (commonly known as a folder)② The File class is declared in Java Under IO package ③ The File class involves the creation, deletion, renaming, modification time, File size and other methods of files or Fi ...

Source code analysis of Sylar server framework log module Overall design of log library module It is used to format the output program log, which is convenient to locate the problems in the running process of the program from the log. In addition to the log content itself, the log here should also include additional information such as ...

1, Understand the working principle of LVS-DR 1.1 LVS-DR packet flow analysis (1) The client sends a request to the Director Server (load balancer), and the requested data message (the source IP is CIR and the target IP is VIP) reaches the kernel space. (2)DirectorServer and RealServer are in the same network, and the data is transmitt ...

Three problems in concurrent programming 1. Visibility /** * When one thread modifies a shared variable, another thread cannot get the latest value immediately */ public class Test01 { private static Boolean flag = true; public static void main (String[] args) { new Thread(() -> { while (flag) { } }).start(); ...