• Priority in SQL script (and, or and brackets)


    On the third day of February, xinchou year, niuxinmao month, renxu day I haven’t had more blog for many days. Why? Because my demand is online, and then it’s Bibi again, which makes me feel sad and shivering… Oh, my God Let’s go back to today’s SQL modification: The requirement is as follows: query the […]

  • Vs Code common plug-ins


    In normal development,VS CodeIt has almost become the main development tool. Here are some plug-ins that I think are easy to use. Vs Code common plug-ins 1.Auto Close Tag Automatic closing of HTML / XML tags 2.Auto Rename Tag Automatically rename paired HTML / XML tags 3.Bracket Pair Colorizer Adding different colors to brackets makes […]

  • Grasp regular expressions quickly


    1. Preface When it comes to regularization, maybe many people will feel headache as I used to. The purpose of this article is not to make you become regularization experts, but just to describe some problemsSimple and regular writingandHow to write some simple rulesCome on! 2. Text 2.1 welfare section First of all, release the […]

  • Recursive downward algorithm to realize calculator


    Using recursive downward algorithm combined with ourBKLexerImplementation of support for four operations and bracket priority calculator program. Code list [golang] package main import ( “fmt” “os” “bufio” “strings” “strconv” “./bklexer” ) type Node interface { GetValue() float64 } type Number struct { value float64 } func NewNumber(token *BKLexer.Token) *Number { value, _ := strconv.ParseFloat(token.Source, 64) […]

  • [regular expression] matching times of basic reference books


    *. grouping Before we talk about the number of matches, let’s talk about the others.Use parentheses () to wrap the character content and make it a subexpression. After matching, in addition to the total matching result, the subexpression matching result will also be stored in memory.Here, the function of brackets is similar to that of […]

  • ES6 (V) — function


    function Function (function method update [default value, uncertain parameter, arrow function]) Default parameters — how to handle the default values of function parameters? ES5 ES6 Number of function parameters Rest parameter — how to deal with uncertain parameters? ES5 ES6 Spread operator (inverse operation of rest parameter) ES5 ES6 Arrow functions statement Parameters You can […]

  • Leetcode 394. String decoding | Python


    394. String decoding Title Source: leetcode https://leetcode-cn.com/problems/decode-string subject Given an encoded string, returns its decoded string. The coding rule is: K [encoded]_ String], indicating the encoded inside the square brackets_ String is repeated exactly k times. Note that K is guaranteed to be a positive integer. You can assume that the input string is always […]

  • The distinction between compound sentences and operators


    The concept and usage of compound sentence In some cases, the statement must be combined with other statements to achieve its functions. The code in curly braces {} is called a compound statement. For example: int a,b; if (a == b) … / * this part of the code is used with the if function, […]

  • Thought analysis and code implementation of infix to suffix expression


    Infix expression to suffix expression As you can see, the suffix expression is suitable for calculation, but it is not easy for people to write it, especially when the expression is very long. Therefore, in development, we need to convert infix expression into suffix expression. The specific steps are as follows: Initialize two stacks: the […]

  • sql injection violation, syntax error:token LPAREN


    Using druid to query MySQL with as, the following error is reported:Error querying database. Cause: java.sql.SQLException: sql injection violation, syntax error: TODO. pos 782, line 25, column 5, token LPAREN : with g as ( 。。。uncategorized SQLException; SQL state [null]; error code [0]; sql injection violation, syntax error: TODO. pos 782, line 25, column 5, […]

  • Common shell script commands


    We need to learn to use tools to free our hands. For example, we can create soft links for some files in the folder in batch. We can write a script to implement it. Here are some commands used in this project. variable When defining a variable, the variable name is not marked with dollar […]

  • Discover the beauty of data structure stack


    In the world of code, stack is a very important data structure no matter what language it is.Stack overflow, the world-famous code query community, takes stack overflow as a part of the website name.In the process of writing code or debugging, I believe you have felt the joy of skipping in the world of function […]