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How to determine whether an object has a given property in JavaScript
...
Object has property:
If you are testing for properties that are on the object itself (not a part of its prototype chain) you can use .hasOwnProperty():
if (x.hasOwnProperty('y')) {
// ......
}
Object or its prototype has a property:
You can use the i...
Timer function to provide time in nano seconds using C++
... <chrono>. Additionally I'll demonstrate how you can templatize the testing code on the clock so that you can rapidly switch between RDTSC and your system's built-in clock facilities (which will likely be based on clock(), clock_gettime() and/or QueryPerformanceCounter.
Note that the RDTSC i...
In Java 8 how do I transform a Map to another Map using a lambda?
...
Map<String, Integer> map = new HashMap<>();
map.put("test1", 1);
map.put("test2", 2);
Map<String, Integer> map2 = new HashMap<>();
map.forEach(map2::put);
System.out.println("map: " + map);
System.out.println("map2: " + map2);
// Output:
// map: {test2=2, test1=1...
What is “:-!!” in C code?
...answer here has a good response:
These macros implement a compile-time test, while assert() is a run-time test.
Exactly right. You don't want to detect problems in your kernel at runtime that could have been caught earlier! It's a critical piece of the operating system. To whatever extent prob...
Including all the jars in a directory within the Java classpath
...e following:
Use straight quotes (")
Use *, not *.jar
Windows
java -cp "Test.jar;lib/*" my.package.MainClass
Unix
java -cp "Test.jar:lib/*" my.package.MainClass
This is similar to Windows, but uses : instead of ;. If you cannot use wildcards, bash allows the following syntax (where lib is the ...
Why are elementwise additions much faster in separate loops than in a combined loop?
...llocations will appear at the same offset from a page-boundary.
Here's the test code:
int main(){
const int n = 100000;
#ifdef ALLOCATE_SEPERATE
double *a1 = (double*)malloc(n * sizeof(double));
double *b1 = (double*)malloc(n * sizeof(double));
double *c1 = (double*)malloc(n * sizeo...
How can I represent an infinite number in Python?
...
In Python, you can do:
test = float("inf")
In Python 3.5, you can do:
import math
test = math.inf
And then:
test > 1
test > 10000
test > x
Will always be true. Unless of course, as pointed out, x is also infinity or "nan" ("not a n...
Get the name of the currently executing method
...
Even better than my first answer you can use __method__:
class Foo
def test_method
__method__
end
end
This returns a symbol – for example, :test_method. To return the method name as a string, call __method__.to_s instead.
Note: This requires Ruby 1.8.7.
...
What is the difference between ${var}, “$var”, and “${var}” in the Bash shell?
...parameter is a positional parameter with more than one digit…
Let's test:
$ set -- {0..100}
$ echo $22
12
$ echo ${22}
20
Huh. Neat. I honestly didn't know that before writing this (I've never had more than 9 positional parameters before.)
Of course, you also need braces to do the powerfu...
Remove characters from C# string
...lation, where dozens of lines of code and multiple loops would be needed. Testing the compiled version of this regex against a simple unoptimised loop 50000 times, the regex is 6X slower.
– Tony Cheetham
Feb 13 '18 at 12:07
...