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Is String.Format as efficient as StringBuilder
... the current version. This may no longer apply to later versions.
String.Format uses a StringBuilder internally:
public static string Format(IFormatProvider provider, string format, params object[] args)
{
if ((format == null) || (args == null))
{
throw new ArgumentNullException((f...
What is the difference between List (of T) and Collection(of T)?
I've seen them used in a lot of the same ways, and I am worried I'm about to go down a path in design that is irreversible if I don't understand this better. Also, I am using .NET.
...
Replacing Pandas or Numpy Nan with a None to use with MysqlDB
I am trying to write a Pandas dataframe (or can use a numpy array) to a mysql database using MysqlDB . MysqlDB doesn't seem understand 'nan' and my database throws out an error saying nan is not in the field list. I need to find a way to convert the 'nan' into a NoneType.
...
Is there a shortcut to make a block comment in Xcode?
...xt and Eclipse, and I think most other IDEs, there are separate keyboard shortcuts for line comments and block comments ( /**/ ). However, I don't see that in Xcode - in fact, I don't even see a menu option to add a block comment. Is it simply not supported in Xcode? That would certainly seem to be ...
How to get the children of the $(this) selector?
...
The jQuery constructor accepts a 2nd parameter called context which can be used to override the context of the selection.
jQuery("img", this);
Which is the same as using .find() like this:
jQuery(this).find("img");
If the imgs you desire ...
Reshape three column data frame to matrix (“long” to “wide” format) [duplicate]
...data frame, which is probably what most readers of this answer will want. For a heatmap, though, you would need to convert this to a true matrix.
library(tidyr)
pivot_wider(tmp, names_from = y, values_from = z)
## # A tibble: 2 x 4
## x a b c
## <fct> <dbl> <dbl> &...
How do I raise the same Exception with a custom message in Python?
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Update: For Python 3, check Ben's answer
To attach a message to the current exception and re-raise it:
(the outer try/except is just to show the effect)
For python 2.x where x>=6:
try:
try:
raise ValueError # someth...
Order of items in classes: Fields, Properties, Constructors, Methods
Is there an official C# guideline for the order of items in terms of class structure?
15 Answers
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How do I check if a C++ std::string starts with a certain string, and convert a substring to an int?
...e misread this to mean "search backwards through the whole string looking for the prefix". That would give the wrong result (e.g. string("tititito").rfind("titi") returns 2 so when compared against == 0 would return false) and it would be inefficient (looking through the whole string instead of just...
What is std::move(), and when should it be used?
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Wikipedia Page on C++11 R-value references and move constructors
In C++11, in addition to copy constructors, objects can have move constructors.
(And in addition to copy assignment operators, they have move assignment operators.)
The move constructor is used instead of the copy const...