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String, StringBuffer, and StringBuilder
...o, using String for logic operations is rather slow, and is not advised at all, since the JVM converts the String to a StringBuffer in the bytecode. A lot of overhead is wasted converting from String to StringBuffer and then back to String again.
– Pieter van Niekerk
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UICollectionView current visible cell index
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The method [collectionView visibleCells] give you all visibleCells array you want. Use it when you want to get
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
for (UICollectionViewCell *cell in [self.mainImageCollection visibleCells]) {
NSIndexP...
Make sure only a single instance of a program is running
...ode version is available singleton.py. Please file bugs here.
You can install tend using one of the following methods:
easy_install tendo
pip install tendo
manually by getting it from http://pypi.python.org/pypi/tendo
sh...
How to call asynchronous method from synchronous method in C#?
I have a public async void Foo() method that I want to call from synchronous method. So far all I have seen from MSDN documentation is calling async methods via async methods, but my whole program is not built with async methods.
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What is the function __construct used for?
I have been noticing __construct a lot with classes. I did a little reading and surfing the web, but I couldn't find an explanation I could understand. I am just beginning with OOP.
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How do I append one string to another in Python?
...ugh memory to resize the string, the original
string object at *pv is deallocated, *pv is set to NULL, an "out of
memory" exception is set, and -1 is returned. Else (on success) 0 is
returned, and the value in *pv may or may not be the same as on input.
As always, an extra byte is alloc...
How to check 'undefined' value in jQuery
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JQuery library was developed specifically to simplify and to unify certain JavaScript functionality.
However if you need to check a variable against undefined value, there is no need to invent any special method, since JavaScript has a typeof operator, which is...
Parameterize an SQL IN clause
...er 7 and later will auto-parameterize queries, so using parameters isn't really necessary from a performance standpoint - it is, however, critical from a security standpoint - especially with user inputted data like this.
sh...
How can I use “sizeof” in a preprocessor macro?
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Following snippets will produce no code if sizeof(someThing) equals PAGE_SIZE; otherwise they will produce a compile-time error.
1. C11 way
Starting with C11 you can use static_assert (requires #include <assert.h>).
Usage:
static_assert(sizeof(someThing) == PAGE_SIZE, "Data structure do...
JavaScript curry: what are the practical applications?
...self—is useful in JavaScript; it is a technique for converting function calls with multiple arguments into chains of function calls with a single argument for each call, but JavaScript supports multiple arguments in a single function call.
In JavaScript—and I assume most other actual languages...