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How does the Java 'for each' loop work?
...ment primitive-int array (A is iterator, B is index):
[C:\java_code\]java TimeIteratorVsIndexIntArray 1000000
Test A: 358,597,622 nanoseconds
Test B: 269,167,681 nanoseconds
B faster by 89,429,941 nanoseconds (24.438799231635727% faster)
[C:\java_code\]java TimeIteratorVsIndexIntArray 1000000
Test...
String is immutable. What exactly is the meaning? [duplicate]
...so "bar" is a reference to the same String instance regardless of how many times it appears in your code.
The "hello" creates one instance that is pooled, and the new String(...) creates a non-pooled instance. Try System.out.println(("hello" == "hello") + "," + (new String("hello") == "hello") + ...
How do you get the magnitude of a vector in Numpy?
...
mag = np.sqrt(x.dot(x))
Here are some benchmarks:
>>> import timeit
>>> timeit.timeit('np.linalg.norm(x)', setup='import numpy as np; x = np.arange(100)', number=1000)
0.0450878
>>> timeit.timeit('np.sqrt(x.dot(x))', setup='import numpy as np; x = np.arange(100)', num...
Trim spaces from start and end of string
...cript performance this test is still relevant or reliable as it was at the time of this answer.
– Eduardo
Nov 30 '12 at 10:11
2
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How to count the number of set bits in a 32-bit integer?
...in, producing 8x 4-bit sums. The i - ... optimization isn't possible this time so it does just mask before / after shifting. Using the same 0x33... constant both times instead of 0xccc... before shifting is a good thing when compiling for ISAs that need to construct 32-bit constants in registers s...
How to create an alias for a command in Vim?
... This is the single best tip for vim. I'm so used to it now that every time I encounter the normal behavior, it takes me a few tried to get my mind retrained.
– airstrike
Feb 24 '15 at 19:58
...
Seeding the random number generator in Javascript
...oose some dummy data to pad the seed with, and advance the generator a few times (12-20 iterations) to mix the initial state thoroughly. This is often seen in reference implementations of PRNGs, but it does limit the number of initial states.
var seed = 1337 ^ 0xDEADBEEF; // 32-bit seed with option...
Are string.Equals() and == operator really same? [duplicate]
...an be overridden, and the implementation used will depend on the execution-time type of the target object), whereas the implementation of == used is determined based on the compile-time types of the objects:
// Avoid getting confused by interning
object x = new StringBuilder("hello").ToString();
ob...
How can I check if a URL exists via PHP?
...ax), this is quick to check server side.
Waiting for a response might take time and block code execution.
Not all headers returned by get_headers() are well formed.
Use curl (if you can).
Prevent fetching the entire body/content, but only request the headers.
Consider redirecting urls:
Do you want t...
str performance in python
...100000 is evaluated by the compiler and is equivalent to a constant at run-time.
>>> import dis
>>> dis.dis(lambda: str(100000))
8 0 LOAD_GLOBAL 0 (str)
3 LOAD_CONST 1 (100000)
6 CALL_FUNCTION 1
...