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Why are static variables considered evil?
...r example, instead, you made your variables non-static, and in your main() function you made a single instance of your class, and then asked your class to execute a particular function 10,000 times, once those 10,000 calls were done, and you delete your references to the single instance, all your st...
Can I have multiple primary keys in a single table?
...
A Table can have a Composite Primary Key which is a primary key made from two or more columns. For example:
CREATE TABLE userdata (
userid INT,
userdataid INT,
info char(200),
primary key (userid, userdataid)
);
Update: Here is a link wit...
How to see which commits in one branch aren't in the other?
...
For fun, I worked out that the '...' (symmetrical difference) rev-parse syntax was added in July 2006, and the documentation for it was updated in June 2008. The joy of open source!
– sehe
S...
What happens to a declared, uninitialized variable in C? Does it have a value?
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Static variables (file scope and function static) are initialized to zero:
int x; // zero
int y = 0; // also zero
void foo() {
static int x; // also zero
}
Non-static variables (local variables) are indeterminate. Reading them prior to assigning a valu...
Combine --user with --prefix error with setup.py install
...ss to. I was trying to take advantage of Python's relatively new per user site-packages directory , and the new option --user . (The option is currently undocumented , however it exists for Python 2.6+; you can see the help by running python setup.py install --help .)
...
Check if a string is html or not
... purposes your app may want to detect these too.
– TK123
Sep 21 '16 at 19:39
HTML is designed with the forgiveness of ...
Why it's not possible to use regex to parse HTML/XML: a formal explanation in layman's terms
... or bonbon. Matching of recursive/balanced structures make these even more fun.
Wikipedia puts this nicely, in a quote by Larry Wall:
'Regular expressions' [...] are only marginally related to real regular expressions. Nevertheless, the term has grown with the capabilities of our pattern matchi...
Adding new column to existing DataFrame in Python pandas
...)
As per this example (which also includes the source code of the assign function), you can also include more than one column:
df = pd.DataFrame({'a': [1, 2], 'b': [3, 4]})
>>> df.assign(mean_a=df.a.mean(), mean_b=df.b.mean())
a b mean_a mean_b
0 1 3 1.5 3.5
1 2 4 1...
Null vs. False vs. 0 in PHP
...ill get inequality.
So why are they useful ?
Well, look at the strrpos() function. It returns False if it did not found anything, but 0 if it has found something at the beginning of the string !
<?php
// pitfall :
if (strrpos("Hello World", "Hello")) {
// never exectuted
}
// smart move ...
Tablet or Phone - Android
...
123
As it has been mentioned before, you do not want to check whether the device is a tablet or a ...