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Why do I get a segmentation fault when writing to a “char *s” initialized with a string literal, but
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See the C FAQ, Question 1.32
Q: What is the difference between these initializations?
char a[] = "string literal";
char *p = "string literal";
My program crashes if I try to assign a new value to p[i].
A: A string literal (the formal term
for a double-quot...
django admin - add custom form fields that are not part of the model
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If for some reason, you get an AttributeError: Unable to lookup "extra_field"..., try adding a label to the extra_field definition. It seems that django tries to "guess" the label for it, by looking at the Model and the Model...
How to get line count of a large file cheaply in Python?
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num_lines = sum(1 for line in open('myfile.txt') if line.rstrip()) for filter empty lines
– Honghe.Wu
Mar 3 '14 at 9:26
62
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How do I change selected value of select2 dropdown with JqGrid?
...irst I initialize select2 on my select:
$('#my-best-friend').select2();
Now I manually select Bob in the browser. Next Bob does something naughty and I don't like him anymore. So the system unselects Bob for me:
$('#my-best-friend').val('').trigger('change');
Or say I make the system select th...
Hidden Features of Java
...d it, never heard of it before.
ThreadLocals are typically not so widely known as a way to store per-thread state.
Since JDK 1.5 Java has had extremely well implemented and robust concurrency tools beyond just locks, they live in java.util.concurrent and a specifically interesting example is the j...
How to encrypt/decrypt data in php?
...= openssl_random_pseudo_bytes($key_size, $strong);
// $strong will be true if the key is crypto safe
This can be done once or multiple times (if you wish to create a chain of encryption keys). Keep these as private as possible.
IV
The initialisation vector adds randomness to the encryption and r...
How to convert Set to Array?
....forEach(v => array.push(v));
Previously, using the non-standard, and now deprecated array comprehension syntax:
let array = [v for (v of mySet)];
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Is “else if” a single keyword?
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They are not a single keyword if we go to the draft C++ standard section 2.12 Keywords table 4 lists both if and else separately and there is no else if keyword. We can find a more accessible list of C++ keywords by going to cppreferences section on keyw...
Any way to delete in vim without overwriting your last yank? [duplicate]
...in the registers:
"_dd
See also :help registers.
It's probably safest, if you want to paste something over and over again, to yank it into a "named" register.
"aY
Yanks a line into the a register. Paste it with "ap.
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How can jQuery deferred be used?
...he best use case I can think of is in caching AJAX responses. Here's a modified example from Rebecca Murphey's intro post on the topic:
var cache = {};
function getData( val ){
// return either the cached value or jqXHR object wrapped Promise
return $.when(
cache[ val ] ||
...