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Is char signed or unsigned by default?
...d.
Do note that char is special in this way. If you declare a variable as int it is 100% equivalent to declaring it as signed int. This is always true for all compilers and architectures.
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Why is 128==128 false but 127==127 is true when comparing Integer wrappers in Java?
...
When you compile a number literal in Java and assign it to a Integer (capital I) the compiler emits:
Integer b2 =Integer.valueOf(127)
This line of code is also generated when you use autoboxing.
valueOf is implemented such that certain numbers are "pooled", and it returns the same ...
How to create and handle composite primary key in JPA
...nts Serializable {
@Column(name = "Id", nullable = false)
private int id;
@Column(name = "Version", nullable = false)
private int version;
/** getters and setters **/
}
Another way to achieve this task is to use @IdClass annotation, and place both your id in that IdClass. ...
What are the best practices for SQLite on Android?
...ow up blog post:
Single SQLite connection
Also checkout the fork by 2point0 of the previously mentioned locking example:
Android-Database-Locking-Collisions-Example by 2point0 on GitHub
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In C, how should I read a text file and print all strings
...
The simplest way is to read a character, and print it right after reading:
int c;
FILE *file;
file = fopen("test.txt", "r");
if (file) {
while ((c = getc(file)) != EOF)
putchar(c);
fclose(file);
}
c is int above, since EOF is a negative number, and a pl...
StringIO in Python3
... StringIO module. For a more direct solution the message TypeError: Can't convert 'bytes' object to str implicitly, see this answer.
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How do I handle ImeOptions' done button click?
...onListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
// Identifier of the action. This will be either the identifier you supplied,
// or EditorInfo.IME_NULL if being called due to the enter key being pressed.
if (actionId ...
Should I use #define, enum or const?
...rk in embedded systems so the following solution is based on the fact that integer and bitwise operators are fast, low memory & low in flash usage.
Place the enum in a namespace to prevent the constants from polluting the global namespace.
namespace RecordType {
An enum declares and defines ...
In STL maps, is it better to use map::insert than []?
...) will only create:
using std::cout; using std::endl;
typedef std::map<int, std::string> MyMap;
MyMap map;
// ...
std::pair<MyMap::iterator, bool> res = map.insert(MyMap::value_type(key,value));
if ( ! res.second ) {
cout << "key " << key << " already exists "
...
Why shouldn't all functions be async by default?
...d now includes not just CPU computations but also some I/O? You'll need to convert the method to async but this would break API and all the callers up the stack would be needed to be updated as well (and they can even be different apps from different vendors). Or you'll need to add async version alo...