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问题 When I work with my favorite containers, I tend to chain operations. For instance, in the well-known Erase–remove idiom: v.erase( std::remove_if(v.begin(), v.end(), is_odd), v.end() ); From what I know of the order of evaluation, v.end() (on the rhs) might be evaluated before the call to std::remove_if . This is not a problem here since std::remove* only shuffle the vector without changing its end iterator. But it could lead to really surprising constructs, like for instance (demo): #include

问题 When I work with my favorite containers, I tend to chain operations. For instance, in the well-known Erase–remove idiom: v.erase( std::remove_if(v.begin(), v.end(), is_odd), v.end() ); From what I know of the order of evaluation, v.end() (on the rhs) might be evaluated before the call to std::remove_if . This is not a problem here since std::remove* only shuffle the vector without changing its end iterator. But it could lead to really surprising constructs, like for instance (demo): #include

问题 I am following a tutorial and it says ES modules uses live bindings. It means a feature to support cyclical dependencies. But I don't clearly understand this concept. What does this mean? 回答1: Live bindings is a concept introduced in ES modules. It means that when the exporting module changes a value, the change will be visible from the importer side. This is not the case for CommonJS modules. Module exports are copied in CommonJS. Hence importing modules cannot see changes happened on the

问题 For my project I record user audio using MediaRecorder and it almost works fine. My problem rises when I wish to display a waveform of the user recording using Wavesurfer.js, which doesn't load my recording. Playing the recording with an Audio element works fine, though. After trying different sources, it seams that it is because the final .webm file doesn't have much metadata, not even a duration or bitrate (even though I set it in the MediaRecorder options). Here is the output from ffprobe

问题 To get a query in django I can do: >>> print User.objects.all().query SELECT `auth_user`.`id`, `auth_user`.`username`, `auth_user`.`first_name`, `auth_user`.`last_name`, `auth_user`.`email`, `auth_user`.`password`, `auth_user`.`is_staff`, `auth_user`.`is_active`, `auth_user`.`is_superuser`, `auth_user`.`last_login`, `auth_user`.`date_joined` FROM `auth_user` However, how would I get the query it builds when doing a COUNT? >>> User.objects.all().count().query Traceback (most recent call last):

问题 When an action for navigating to a route is triggered, an action triggers a new state where the router.location.pathname changes according to the browser's history . Another property changes as well: router.location.key , to a new random string. Even when the pathname itself doesn't change (clicking on a link to a page from the page itself), the key still updates. What's the purpose of the key property? In which situations would I want my own state to have a randomly generated key which

问题 When an action for navigating to a route is triggered, an action triggers a new state where the router.location.pathname changes according to the browser's history . Another property changes as well: router.location.key , to a new random string. Even when the pathname itself doesn't change (clicking on a link to a page from the page itself), the key still updates. What's the purpose of the key property? In which situations would I want my own state to have a randomly generated key which

问题 Problem I need to convert two ints and a string of variable length to bytes. What I did I converted each data type into a byte array and then added them into a byte buffer. Of which right after that I will copy that buffer to one byte array, as shown below. byte[] nameByteArray = cityName.getBytes(); byte[] xByteArray = ByteBuffer.allocate(4).putInt(x).array(); byte[] yByteArray = ByteBuffer.allocate(4).putInt(y).array(); ByteBuffer byteBuffer = ByteBuffer.allocate(nameByteArray.length +

问题 Problem I need to convert two ints and a string of variable length to bytes. What I did I converted each data type into a byte array and then added them into a byte buffer. Of which right after that I will copy that buffer to one byte array, as shown below. byte[] nameByteArray = cityName.getBytes(); byte[] xByteArray = ByteBuffer.allocate(4).putInt(x).array(); byte[] yByteArray = ByteBuffer.allocate(4).putInt(y).array(); ByteBuffer byteBuffer = ByteBuffer.allocate(nameByteArray.length +

问题 Having gone through multiple posts on stack I still couldn't find a right answer. Checked the documentation on CORS extension as well. I have the following server code up and running: var WebSocketServer = require("ws").Server var http = require("http") var express = require('express') var cors = require('cors') var app = express(); app.use(cors()); var port = process.env.PORT || 9000 var server = http.createServer(app) server.listen(port) var count = 0; var clients = {}; var rooms = {}; var