Tag:Question mark

  • Resolve nullable types

    Time:2022-1-15

    C# single question mark? And double question mark??? The single question mark is used to assign null to data types that cannot be directly assigned null, such as int, double, bool, etc., which means that this data type is nullable. int? i = 3;Equivalent to: Nullable<int> i = new Nullable<int>(3);int i; // Default 0int? ii; […]

  • Solve the pop-up of windows app store by running Python under win10 command line

    Time:2021-10-24

    preface A few days ago, in order to experience the new version of edge, we updated win10, and then ran the python command. As a result, we jumped out of the win10 store (black question mark???) way So I checked the environment variables and found that there was no problem with the configuration. I suspected […]

  • The type of Android input is date to hide the drop-down arrow

    Time:2021-5-29

    Recently, there is a requirement to have a date selector, and then the style is custom. The arrow will be hidden automatically on IOS, but Android won’t, as shown in the figure below And then a variety of online search is summarized as follows input[type=”date”]::-webkit-inner-spin-button, input[type=”date”]::-webkit-outer-spin-button, input[type=”date”]::-webkit-calendar-picker-indicator{ visibility: hidden;-webkit-appearance: none;display: none;} However, there is no […]

  • Question mark statement

    Time:2021-4-28

    #include<iostream> using namespace std; int main(void) { int a = -1; a > 0 ? a = a : a = -a; cout << a; return 0; } The output is 1 Question mark statement means whether the statement before the question mark is true. If it is true, the statement before the colon will […]

  • New JavaScript syntax “double question mark syntax” and “optional chain syntax”

    Time:2021-2-27

    Double question mark grammar Double question mark grammarThe concept is to return the value on the right when the value on the left is null or undefined let Form = undefined ?? true; //Form = true Alternative chain syntax ? optional chain //Optional chain let body = { value: { a: ‘123321’ } } let […]

  • Tp6 omits from URL index.php

    Time:2021-2-13

        Just add a question mark  

  • JSP Chinese display question mark problem solution

    Time:2020-10-28

    Question: the Chinese that you want to output in JSP is displayed as “?” Solution: search JSP in eclipse windows preferences, and select Chinese in the encoding option. In this way, the new JSP file will support Chinese display. Modify the existing JSP file as follows: change all encoding methods to GB18030, as follows: Copy […]

  • Regular expression formula and tutorial

    Time:2020-10-21

    Reprinted at: https://blog.csdn.net/weng_xianhu/article/details/10096863 In fact, regular is snobbish, cutting the head to get moneyIf you can’t recognize a special symbol, use an inverted bar to guide the wayThe reverse bar is followed by a small w, which is represented by a numeric letter; (- W followed by a numeric letter; – D followed by a […]

  • The input type of Android phone is date to hide the drop-down arrow

    Time:2020-8-30

    A recent requirement is to have a date selector with a custom style. The arrow will be hidden automatically on IOS, but Android will not, as shown in the figure below Then a variety of online search summed up the following ways input[type=”date”]::-webkit-inner-spin-button, input[type=”date”]::-webkit-outer-spin-button, input[type=”date”]::-webkit-calendar-picker-indicator{ visibility: hidden;-webkit-appearance: none;display: none;} However, there is no effect of […]

  • Summary of several usage of question mark in JS regular expression

    Time:2020-5-26

    The matching greedy pattern can be stopped by adding a question mark after the repeated characters, such as +?, *?, {2,3}. var pattern=/\w{2,3}/; console.log(“aaaa”.match(pattern)[0]); /*Results “AAA”; there will be as many matches as possible in greedy mode, So it matches three duplicate characters */ var pattern2=/\w{2,3}?/; console.log(“aaaa”.match(pattern2)[0]); /* *Results “AA”; after the question mark is […]

  • Brief introduction to ABAP’s open SQL and hybrid commerce’s flexible search

    Time:2020-3-13

    In ABAP application, our application developer uses open SQL to access database. These open SQL will be converted into database provider specific SQL by database interface and then executed. Enterprise search / simple search is also supported in CRM and C4C, In fact, the implementation principle is to call an RFC to Trex server to […]

  • Jump and transfer of pit 91

    Time:2020-1-18

    When he was dying, he sat up and asked with a smile where bug came from?! 1. First it’s capital letters Two days ago, a new version of “seven comments” v2.0.0 was released. As a result, you know, a program without bugs is not a good program, and a programmer who can’t write bugs is […]