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用App Inventor 2做扫描仪App？从拍照到展示，手把手教你搭一套完整相机功...
用App Inventor 2做扫描仪App？从拍照到展示，手把手教你搭一套完整相机功能
上周有个做社区志愿服务的朋友问我："能不能用手机拍下老人的健康档案，然后直接在App里分类显示？"他需要一个轻量的、不给老人增加学习...
Randomize a List
What is the best way to randomize the order of a generic list in C#? I've got a finite set of 75 numbers in a list I would like to assign a random order to, in order to draw them for a lottery type application.
...
JSON Array iteration in Android/Java
I am building an android app that needs to download and synchronise with an online database, I am sending my query from the app to a php page which returns the relevant rows from a database in JSON format.
...
java.sql.SQLException: Incorrect string value: '\xF0\x9F\x91\xBD\xF0\x9F…'
...ny supplementary characters in
utf8 columns and you need not worry about converting characters or
losing data when upgrading utf8 data from older versions of MySQL.
So to support these characters, your MySQL needs to be 5.5+ and you need to use utf8mb4 everywhere. Connection encoding needs to ...
Returning a value from thread?
...losures. Create a variable that will hold the return value from the thread and then capture it in a lambda expression. Assign the "return" value to this variable from the worker thread and then once that thread ends you can use it from the parent thread.
void Main()
{
object value = null; // Used...
Check if two unordered lists are equal [duplicate]
...ype for an unordered collection of (hashable) things, called a set. If you convert both lists to sets, the comparison will be unordered.
set(x) == set(y)
Documentation on set
EDIT: @mdwhatcott points out that you want to check for duplicates. set ignores these, so you need a similar data struc...
Which is faster: Stack allocation or Heap allocation
...ance out of heap allocation, but that comes with a slight added complexity and its own headaches.
Also, stack vs. heap is not only a performance consideration; it also tells you a lot about the expected lifetime of objects.
...
onActivityResult is not being called in Fragment
...ityResult(), but it did not make a call to super.onActivityResult() for unhandled result codes. Apparently, even though the fragment is the one making the startActivityForResult() call, the activity gets the first shot at handling the result. This makes sense when you consider the modularity of frag...
Undefined behavior and sequence points
...
C++98 and C++03
This answer is for the older versions of the C++ standard. The C++11 and C++14 versions of the standard do not formally contain 'sequence points'; operations are 'sequenced before' or 'unsequenced' or 'indetermina...
Connect to Amazon EC2 file directory using Filezilla and SFTP
...m file and select it.
A message box will appear asking your permission to convert the file into ppk format. Click Yes, then give the file a name and store it somewhere.
If the new file is shown in the list of Keyfiles, then continue to the next step. If not, then click "Add keyfile..." and select ...