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Direct casting vs 'as' operator?
... tend to almost never use 2 since if something is not the right type, I usually expect an exception to occur. I have only seen a need for this return-null type of functionality with badly designed libraries which use error codes (e.g. return null = error, instead of using exceptions).
3 is not a ca...
NSDictionary - Need to check whether dictionary contains key-value pair or not
...uldn't we mistakenly think that the key isn't present in the dictionary at all?
– jbx72487
Feb 1 '13 at 18:51
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Which is best way to define constants in android, either static class, interface or xml resource?
... advantages of using project resources is the ease of access and that they allow you to organize your project significantly.
static final constants are compiled into the java bytecode; project resources are compiled into a binary format within the apk. Accessing either is extremely efficient... if ...
关于App Inventor 2过程积木，被问最多的6个问题 - App应用开发 - 清泛IT社...
...>做过程名。完整列表在 <a href="https://en.wikipedia.org/wiki/List_of_Java_keywords" target="_blank">Java关键字列表</a> ，常见的有 <font face="Courier New">if</font>、<font face="Courier New">else</font>、<font face="Courier New">while</font>、<font face="Courier New">for</font...
NSUserDefaults - How to tell if a key exists
I'm working on a small iPhone app, and I am using NSUserDefaults as my data persistence. It only has to keep track of a few things, such as some names and some numbers so I figure I might as well keep it simple.
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python pandas dataframe to dictionary
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See the docs for to_dict. You can use it like this:
df.set_index('id').to_dict()
And if you have only one column, to avoid the column name is also a level in the dict (actually, in this case you use the Series.to_dict()):
df.set_index('id')...
How to resize a VirtualBox vmdk file
... iso from within the virtualbox settings).
P.S. If your new size is too small, you'll get the same error even with your new vdi file.
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How to convert a number to string and vice versa in C++
...o-number conversion and vice-versa are built in into the standard library. All the following functions are present in <string> (as per paragraph 21.5).
string to numeric
float stof(const string& str, size_t *idx = 0);
double stod(const string& str, size_t *id...
How to change Vagrant 'default' machine name?
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I found the multiple options confusing, so I decided to test all of them to see exactly what they do.
I'm using VirtualBox 4.2.16-r86992 and Vagrant 1.3.3.
I created a directory called nametest and ran
vagrant init precise64 http://files.vagrantup.com/precise64.box
to generate a...
PostgreSQL query to list all table names?
Is there any query available to list all tables in my Postgres DB.
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