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When would anyone use a union? Is it a remnant from the C-only days?
I have learned but don't really get unions. Every C or C++ text I go through introduces them (sometimes in passing), but they tend to give very few practical examples of why or where to use them. When would unions be useful in a modern (or even legacy) case? My only two guesses would be programming ...
Python unittest - opposite of assertRaises?
...the correct solution in fact. The solution proposed by user9876 is conceptually flawed: if you test for the non-raising of say ValueError, but ValueError is instead raised, your test must exit with a failure condition, not an error one. On the other hand, if in running the same code you would raise ...
How do I add a placeholder on a CharField in Django?
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Look at the widgets documentation. Basically it would look like:
q = forms.CharField(label='search',
widget=forms.TextInput(attrs={'placeholder': 'Search'}))
More writing, yes, but the separation allows for better abstraction of more complic...
Count character occurrences in a string in C++
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Small note, but the return type is typically signed. For some reason std::count returns type iterator_traits<InputIt>::difference_type, which for most standard containers is std::ptrdiff_t, not std::size_t.
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Hidden Features of PHP? [closed]
...and getting a reference most of the time is great.
– Allain Lalonde
Sep 14 '08 at 17:46
1
This is...
Odd behavior when Java converts int to byte?
...+ unsignedByte);
Would print out: "Signed: -1 Unsigned: 255"
What's actually happening here?
We are using bitwise AND to mask all of the extraneous sign bits (the 1's to the left of the least significant 8 bits.)
When an int is converted into a byte, Java chops-off the left-most 24 bits
111111...
Use numpy array in shared memory for multiprocessing
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To add to @unutbu's (not available anymore) and @Henry Gomersall's answers. You could use shared_arr.get_lock() to synchronize access when needed:
shared_arr = mp.Array(ctypes.c_double, N)
# ...
def f(i): # could be anything numpy accepts as an index such another numpy array
with ...
How update the _id of one MongoDB Document?
I want update an _id field of one document. I know it's not a really good pratice. But with some technical reason, I need update it. If I try to update it I get:
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Creating C macro with ## and __LINE__ (token concatenation with positioning macro)
...lizing) unless the result needs to be "stringified". Gcc has features but ALL can be done with plain C version 1 (and some argue Berkeley 4.3 C is so much faster it's worth learning how to use).
**Clang (llvm) DOES NOT DO WHITE SPACE CORRECTLY for macro expansion - it adds whitespace (which certai...
StringBuilder vs String concatenation in toString() in Java
...o builder?
At the point where you're concatenating in a loop - that's usually when the compiler can't substitute StringBuilder by itself.
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