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C++11 rvalues and move semantics confusion (return statement)
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First example
std::vector<int> return_vector(void)
{
std::vector<int> tmp {1,2,3,4,5};
return tmp;
}
std::vector<int> &&rval_ref = return_vector();
The first example returns a temporary which is c...
SQL Server add auto increment primary key to existing table
As the title, I have an existing table which is already populated with 150000 records. I have added an Id column (which is currently null).
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python exception message capturing
This doesn't seem to work, I get syntax error, what is the proper way of doing this for logging all kind of exceptions to a file
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Inspecting standard container (std::map) contents with gdb
...lso a bit frustrating that commands like "plist foo std::string" give syntax errors. It appears that the value_type can't contain any punctuation.
– Bklyn
Jan 9 '09 at 21:49
2
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TypeError: 'dict_keys' object does not support indexing
...d.keys() to your shuffle function. Probably this was written with python2.x (when d.keys() returned a list). With python3.x, d.keys() returns a dict_keys object which behaves a lot more like a set than a list. As such, it can't be indexed.
The solution is to pass list(d.keys()) (or simply list(d...
Check if a variable is a string in JavaScript
...e) // displays "string"
alert(typeof stringObject) // displays "object"
Example from this webpage. (Example was slightly modified though).
This won't work as expected in the case of strings created with new String(), but this is seldom used and recommended against[1][2]. See the other answers for...
Loop inside React JSX
I'm trying to do something like the following in React JSX (where ObjectRow is a separate component):
66 Answers
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How to pick just one item from a generator?
... generator using
g = myfunct()
Everytime you would like an item, use
next(g)
(or g.next() in Python 2.5 or below).
If the generator exits, it will raise StopIteration. You can either catch this exception if necessary, or use the default argument to next():
next(g, default_value)
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Python Dictionary Comprehension
...nsion, they create a new dictionary; you can't use them to add keys to an existing dictionary. Also, you have to specify the keys and values, although of course you can specify a dummy value if you like.
>>> d = {n: n**2 for n in range(5)}
>>> print d
{0: 0, 1: 1, 2: 4, 3: 9, 4: ...
PHP - concatenate or directly insert variables in string
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Between those two syntaxes, you should really choose the one you prefer :-)
Personally, I would go with your second solution in such a case (Variable interpolation), which I find easier to both write and read.
The result will be the same; and eve...