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When do I use a dot, arrow, or double colon to refer to members of a class in C++?
...y the double colon ::, the dot ., and the arrow ->, are used for three different scenarios that are always well-defined. Knowing this allows you to immediately know quite a lot about a and b just by looking at a::b, a.b, or a->b, respectively, in any code you look at.
a::b is only used if b...
How can I randomize the lines in a file using standard tools on Red Hat Linux?
...
It uses a module, but the module is part of the Perl code distribution. If that's not good enough, you may consider rolling your own.
I tried using this with the -i flag ("edit-in-place") to have it edit the file. The documentation suggests it should work, but it doesn't. It still displays the s...
Why does only the first line of this Windows batch file execute but all three lines execute in a com
...new window to spawn, and each of the three commands will run in parallel. If you need them to run synchronously, use call.
– akf
Oct 27 '10 at 19:33
11
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How to add/update an attribute to an HTML element using JavaScript?
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You can read here about the behaviour of attributes in many different browsers, including IE.
element.setAttribute() should do the trick, even in IE. Did you try it? If it doesn't work, then maybe
element.attributeName = 'value' might work.
...
UnicodeDecodeError: 'charmap' codec can't decode byte X in position Y: character maps to
...atin-1, UTF-8 (where 0x90 is a continuation byte) is more likely.
You specify the encoding when you open the file:
file = open(filename, encoding="utf8")
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Check that an email address is valid on iOS [duplicate]
...
return [emailTest evaluateWithObject:self];
}
@end
And then utilize:
if([@"emailString@email.com" isValidEmail]) { /* True */ }
if([@"InvalidEmail@notreallyemailbecausenosuffix" isValidEmail]) { /* False */ }
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How I can delete in VIM all text from current line to end of file?
...of file
dCtrl+End will delete from the cursor to the end of the file
But if this file is as large as you say, you may be better off reading the first few lines with head rather than editing and saving the file.
head hugefile > firstlines
(If you are on Windows you can use the Win32 port of h...
Turning multi-line string into single comma-separated
...se awk and sed:
awk -vORS=, '{ print $2 }' file.txt | sed 's/,$/\n/'
Or if you want to use a pipe:
echo "data" | awk -vORS=, '{ print $2 }' | sed 's/,$/\n/'
To break it down:
awk is great at handling data broken down into fields
-vORS=, sets the "output record separator" to ,, which is what ...
promise already under evaluation: recursive default argument reference or earlier problems?
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Thanks! Two questions (1) if function test further takes an argument for f, will you add something like test<- function(g.=g, T=1, f..=f){ g.(1,T, f.=f..) }? In cases with more recursions, is it a good and safe practice adding more .? (2) if f is ...
MySQL: Insert record if not exists in table
...Rupert | Somewhere | 022 |
+----+--------+-----------+------+
Insert a different record:
INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'John', 'Doe', '022') AS tmp
WHERE NOT EXISTS (
SELECT name FROM table_listnames WHERE name = 'John'
) LIMIT 1;
Query OK, 1 row af...