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Why is sizeof considered an operator?
...fine. They're often seen, firstly because they're needed as part of a type cast expression, and secondly because sizeof has very high precedence, so sizeof a + b isn't the same as sizeof (a+b). But they aren't part of the invocation of sizeof, they're part of the operand.
You can't take the address ...
Generate 'n' unique random numbers within a range [duplicate]
...
You could use the random.sample function from the standard library to select k elements from a population:
import random
random.sample(range(low, high), n)
In case of a rather large range of possible numbers, you could use itertools.islice with an infinite random generator:
import itertools...
How do you find the row count for all your tables in Postgres
...th their own tradeoffs.
If you want a true count, you have to execute the SELECT statement like the one you used against each table. This is because PostgreSQL keeps row visibility information in the row itself, not anywhere else, so any accurate count can only be relative to some transaction. Yo...
C++11 emplace_back on vector?
...he member, the argument is treated as an lvalue again, in the absence of a cast, so the member just gets copy-constructed. Even if the member was move-constructed, it's not idiomatic to require callers always to pass a temporary or std::move()d lvalue (though I will confess that I have a few corner-...
How do I print a double value with full precision using cout?
...
The iostreams way is kind of clunky. I prefer using boost::lexical_cast because it calculates the right precision for me. And it's fast, too.
#include <string>
#include <boost/lexical_cast.hpp>
using boost::lexical_cast;
using std::string;
double d = 3.14159265358979;
cout &l...
SQL Server - stop or break execution of a SQL script
...SERROR to actually stop the script. E.g.,
:on error exit
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[SOMETABLE]') AND type in (N'U'))
RaisError ('This is not a Valid Instance Database', 15, 10)
GO
print 'Keep Working'
will output:
Msg 50000, Level 15, St...
How to sort an IEnumerable
...r
var result = from s in myEnumerable
orderby s
select s;
or (ignoring case)
var result = myEnumerable.OrderBy(s => s,
StringComparer.CurrentCultureIgnoreCase);
Note that, as is usual with LINQ, this creates a new IEnumerable<T&...
Rounding a double to turn it into an int (java)
...d, it returns a Long when the input param is Double.
So, you will have to cast the return value:
int a = (int) Math.round(doubleVar);
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What does void* mean and how to use it?
.... A void * can be converted to any other pointer type without an explicit cast. You cannot dereference a void * or do pointer arithmetic with it; you must convert it to a pointer to a complete data type first.
void * is often used in places where you need to be able to work with different pointer...
How to drop columns by name in a data frame
..."z","u"))]
x y
1 1 2
2 2 3
3 3 4
4 4 5
5 5 6
Or, much simpler, use the select argument of the subset function : you can then use the - operator directly on a vector of column names, and you can even omit the quotes around the names !
R> subset(df, select=-c(z,u))
x y
1 1 2
2 2 3
3 3 4
4 4 ...