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Purpose of Unions in C and C++
...he union is actually used:
struct VAROBJECT
{
enum o_t { Int, Double, String } objectType;
union
{
int intValue;
double dblValue;
char *strValue;
} value;
} object;
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Logical operators for boolean indexing in Pandas
...Error: The truth value of an array is ambiguous. Use a.empty, a.any() or a.all().
when used as a boolean value. That's because its unclear when it should be True or False. Some users might assume they are True if they have non-zero length, like a Python list. Others might desire for it to be True ...
How to do relative imports in Python?
... the module were a top level module, regardless of where the module is actually located on the file system.
In Python 2.6, they're adding the ability to reference modules relative to the main module. PEP 366 describes the change.
Update: According to Nick Coghlan, the recommended alternative is ...
Define a lambda expression that raises an Exception
...ur goal is to avoid a def, this obviously doesn't cut it. It does, however allow you to conditionally raise exceptions, e.g.:
y = lambda x: 2*x if x < 10 else raise_(Exception('foobar'))
Alternatively you can raise an exception without defining a named function. All you need is a strong stom...
Extracting text from HTML file using Python
...'d like to extract the text from an HTML file using Python. I want essentially the same output I would get if I copied the text from a browser and pasted it into notepad.
...
Undefined reference to `pow' and `floor'
...
Look in /lib or /usr/lib. The libraries are all named lib<name>.a or lib<name>.so - it's the "<name>" you put after the -l. In this case, the math library is named libm.so, so we call it -lm.
– ams
Dec 29 '11 at ...
C state-machine design [closed]
... an enum. It also makes for much cleaner code since you don't need all the extra cruft of function pointers or huge switch statements and while loops. Did I mention it's more efficient too?
Here's what a state machine might look like:
void state_machine() {
first_state:
// Do some stuff here
...
When should I use perror(“…”) and fprintf(stderr, “…”)?
... to perror(NULL) since a call to strerror(errno) will generate the printed string value for errno, and you can then combined that with any other custom error message via fprintf.
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Why is __init__() always called after __new__()?
... new instance.
__new__ is the first step of instance creation. It's called first, and is
responsible for returning a new
instance of your class.
In contrast,
__init__ doesn't return anything; it's only responsible for initializing the
instance after it's been created.
In ge...
Why are static variables considered evil?
...n the container itself is not global. Compared to "normal" code, the only extra thing that a container-managed object is visible to is to the container itself. In fact, DI is very commonly used to avoid the Singleton Pattern.
– Floegipoky
Nov 27 '13 at 21:50
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