The following error is displayed when I open the create-react-app with npm start. I'm new to React and have had no problem using the command line to create a new app in the last few days. I tried to start npx, start npm, and reinstall npm for the updated version. Compilation failed ./src/index.css [/index.css] BrowserslistError: Unknown browser query `android all`. You may be using an old navigation list or a typo in a query. on Array.reduce (<anonymous>) on Array.some (<anonymous>) on Array.filter (<anonymous>)

I have a list of channels like: List <String> locations = Arrays.asList ("US: 5423", "US: 6321", "CA: 1326", "AU: 5631"); And I want to convert Map <String, List <String >> like this: AU = [5631] CA = [1326] US = [5423, 6321] How can I do that?

Due to a bug, I just discovered that this code works well with Visual Studio 17 and probably also with other compilers. Now I am curious to know why? #include <iostream> #include <string> std :: string foo () { returns nullptr; }int main () { car s = foo (); std :: cout << s << std :: endl;} I guess it’s because the c’tor std:: basic_string can be called with a * character, implicitly converting ptr to std :: string (with NULL as argument, then poof). Am I on the right track?

I have the chain and the board. Strings have the same number of letters as arrays. I have to divide s to create a list that has the same length as each element. s = ‘Python programming language’ arr = [‘lkjhgf’, ‘zx’, ‘qw’, ‘ertyuiopakk’, ‘foacdhlc’] How can I get my expected result?

I wrote a simple code to compare random array differences and found something that I do not quite understand.I generate 2 tables filled with random numbers. Add differences between random numbers Print the average difference I would have expected the result to be a random number close to 0.5, but in practice it is 0.3333. Why is the array of random numbers set to 0.3 and not to 0.5?

I'm trying to run the new Canvas Xcode 11 feature, but the canvas is not showing. What am I doing wrong?I just created a new standard project (single-view application), compiled it and activated 'Editor> Editor and Canvas'. I can browse all the files in the project, nothing is displayed. What else do you have to do?

I updated 'android.support:appcompat-v7' to 28.0.0. However, this resulted in a design error. In my Logcat: Fusion manifest, this error failed. How can I solve this problem?

If I get a Boolean variable and put its second bit at 1, the variable is evaluated as true and false at the same time. Compile the following code with gcc6.3 with the -g option (gcc-v6.3.0 / linux / RHEL6.0-2016-x86_64 / bin / g ++ -g main.cpp -o mytest_d) and run the executable. File off. You get the following.How can one be true and false at the same time?

I want to define an effective whole floor function, i. e. A float or double conversion, which truncates to minus infinity. Can you imagine ideas to increase your performance in terms of speed, accuracy or range?

I need to implement many derived classes with different constant member data. Data processing should be in the base class, but I can not find an elegant way to access the derived data. The following code works, but I do not really like it. The code must be run in a small integrated environment. Therefore, using full or shifted libraries such as Boost is not an option. How can I remove the inheritance related code?