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How to convert JSON string to array
...d keys). That's what the documentation says and that's what my PHP 5.2 installation returns. Are you using a function other than the official, built-in json_decode()? What does var_dump(json_decode($str, true)); return?
– RickN
Sep 22 '11 at 15:34
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GoogleTest: How to skip a test?
...o). I then removed my comment, figuring it's obsolete... but that's some really good info! +1
– Kiril
Aug 26 '11 at 17:05
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Add new field to every document in a MongoDB collection
...field" : 1, "test" : "a" }
EDIT:
In case you want to add a new_field to all your collection, you have to use empty selector, and set multi flag to true (last param) to update all the documents
db.your_collection.update(
{},
{ $set: {"new_field": 1} },
false,
true
)
EDIT:
In the above ...
What does mvn install in maven exactly do
I just started using Maven and I was told to do mvn install in a specific directory.
7 Answers
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Is it better to use std::memcpy() or std::copy() in terms to performance?
...y.
I wrote a C++ SHA-2 implementation. In my test, I hash 5 strings using all four SHA-2 versions (224, 256, 384, 512), and I loop 300 times. I measure times using Boost.timer. That 300 loop counter is enough to completely stabilize my results. I ran the test 5 times each, alternating between the m...
Getting the object's property name
...
More specifically, Object.keys(obj) returns an array of property names, i.e. keys, belonging to the passed in obj.
– a learner has no name
Mar 26 '16 at 12:43
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What is better, adjacency lists or adjacency matrices for graph problems in C++?
...e of a specific edge
between any two nodes O(1)
It is slow to iterate over all edges
It is slow to add/delete a node; a complex operation O(n^2)
It is fast to add a new edge O(1)
Adjacency List
Memory usage depends on the number of edges (not number of nodes),
which might save a lot of memor...
How to list all methods for an object in Ruby?
How do I list all the methods that a particular object has access to?
8 Answers
8
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How much is the overhead of smart pointers compared to normal pointers in C++?
..._ptr always has memory overhead for reference counter, though it is very small.
std::unique_ptr has time overhead only during constructor (if it has to copy the provided deleter and/or null-initialize the pointer) and during destructor (to destroy the owned object).
std::shared_ptr has time overhe...
Only read selected columns
...g","Sep","Oct","Nov","Dec"))
dat <- fread("data.txt", drop = c(8:13))
All result in:
> data
Year Jan Feb Mar Apr May Jun
1 2009 -41 -27 -25 -31 -31 -39
2 2010 -41 -27 -25 -31 -31 -39
3 2011 -21 -27 -2 -6 -10 -32
UPDATE: When you don't want fread to return a data.table, use the data.ta...