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What does LINQ return when the results are empty
I have a question about LINQ query. Normally a query returns a IEnumerable<T> type. If the return is empty, not sure if it is null or not. I am not sure if the following ToList() will throw an exception or just a empty List<string> if nothing found in IEnumerable result?
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How to exit an if clause
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Ideally you can achieve both, but there are times when you must trade good code for good performance. Those times are rare, especially when you are considering using Python. In other words: don't worry so much about function c...
No identities were available - administrator request
...one)
In your project's build settings update your code signing identities (all of them) to the new one if there is one. (The old one was probably expired which is one of the biggest causes for the error message you saw)
Verify that your bundle ID is correct (CaSe SeNsEtIvE)
Back to XCode Organizer -...
Why .NET String is immutable? [duplicate]
As we all know, String is immutable. What are the reasons for String being immutable and the introduction of StringBuilder class as mutable?
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Output array to CSV in Ruby
...enerate_line(row) }.join("")
#=> "a1,a2,a3\nb1,b2,b3\nc1,c2,c3\n"
Do all of the above and save to a csv, in one line.
File.open("ss.csv", "w") {|f| f.write(rows.inject([]) { |csv, row| csv << CSV.generate_line(row) }.join(""))}
NOTE:
To convert an active record database to csv would...
Static constant string (class member)
...files
const string A::RECTANGLE = "rectangle";
The syntax you were originally trying to use (initializer inside class definition) is only allowed with integral and enum types.
Starting from C++17 you have another option, which is quite similar to your original declaration: inline variables
// ...
What do commas and spaces in multiple classes mean in CSS?
..._12 .grid_6,
.container_16 .grid_8 {
width: 460px;
}
That says "make all .grid_6's within .container_12's and all .grid_8's within .container_16's 460 pixels wide." So both of the following will render the same:
<div class="container_12">
<div class="grid_6">460px Wide</div&g...
How to add extension methods to Enums
... methods for existing classes in a way other people on your team might actually discover and use. Given that enums are classes like any other it shouldn’t be too surprising that you can extend them, like:
enum Duration { Day, Week, Month };
static class DurationExtensions
{
public static Date...
Why can't variables be declared in a switch statement?
...lity and consistency in the code. In the old days, you might have automatically got an "extra" stack frame, but now that should not be the case for any decent optimizing compiler.
– Tall Jeff
Sep 18 '08 at 14:37
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How to use the PI constant in C++
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On some (especially older) platforms (see the comments below) you might need to
#define _USE_MATH_DEFINES
and then include the necessary header file:
#include <math.h>
and the value of pi can be accessed via:
M_PI
In my math....