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Check if two unordered lists are equal [duplicate]
I'm looking for an easy (and quick) way to determine if two unordered lists contain the same elements:
8 Answers
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Divide a number by 3 without using *, /, +, -, % operators
... because:
n = 4 * a + b
n / 3 = a + (a + b) / 3
So sum += a, n = a + b, and iterate
When a == 0 (n < 4), sum += floor(n / 3); i.e. 1, if n == 3, else 0
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How do I use JDK 7 on Mac OSX?
...Apple's Java 1.6, I had to run /Library/Java/JavaVirtualMachines/1.7.0.jdk and drag "Java SE 7" to the top of the list on the "General" tab. This will also make javac point to the Java 1.7 version when running the terminal.
– sschuberth
Jun 1 '12 at 8:19
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Visual Studio 2013 doesn't discover unit tests
...isual studio 2013 that is composed by one web project, one library project and one unit test project. When I open the solution and try to run the unit tests they are not discover by visual studio. To run the tests I try to go to the menu and choose Test -> Run -> Run all tests or by opening the test...
How to Define Callbacks in Android?
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In many cases, you have an interface and pass along an object that implements it. Dialogs for example have the OnClickListener.
Just as a random example:
// The callback interface
interface MyCallback {
void callbackCall();
}
// The class that takes the c...
How to convert std::string to lower case?
...tion tolower() , however in the past I have had issues with this function and it is hardly ideal anyway as use with a std::string would require iterating over each character.
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Linux command (like cat) to read a specified quantity of characters
Is there a command like cat in linux which can return a specified quantity of characters from a file?
9 Answers
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How do I check if a SQL Server text column is empty?
I am using SQL Server 2005. I have a table with a text column and I have many rows in the table where the value of this column is not null, but it is empty. Trying to compare against '' yields this response:
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Can't use method return value in write context
...in order to check whether that reference points to something that exists), and PHP before 5.5 didn't support references to temporary values returned from functions.
However, the real problem you have is that you use empty() at all, mistakenly believing that "empty" value is any different from "fals...
Extract a dplyr tbl column as a vector
... a neat function to make pulling out a column a bit nicer (easier to type, and easier to read):
pull <- function(x,y) {x[,if(is.name(substitute(y))) deparse(substitute(y)) else y, drop = FALSE][[1]]}
This lets you do either of these:
iris2 %>% pull('Species')
iris2 %>% pull(Species)
iri...