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Getting the last element of a list
...ist[-1] gets the last element, some_list[-2] gets the second to last, etc, all the way down to some_list[-len(some_list)], which gives you the first element.
You can also set list elements in this way. For instance:
>>> some_list = [1, 2, 3]
>>> some_list[-1] = 5 # Set the last e...
Easiest way to check for an index or a key in an array?
... associative array)
[ ${array[key]+abc} ] && echo "exists"
Basically what ${array[key]+abc} does is
if array[key] is set, return abc
if array[key] is not set, return nothing
References:
See Parameter Expansion in Bash manual and the little note
if the colon is omitted, the ope...
warning: incompatible implicit declaration of built-in function ‘xyz’
...al), cool! Thanks.
– Terry Wang
Feb 16 '14 at 0:05
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Is there any haskell function to concatenate list with separator?
...gonkai Not sure what exactly you're referring to, but yes, these functions all allow arbitrary strings as both the separator and the elements. For example, intercalate "," ["some", "", "string"] = "some,,string" and intercalate "" ["foo", "bar"] = "foobar"
– Niklas B.
...
How to alias a table in Laravel Eloquent queries (or using Query Builder)?
...supports aliases on tables and columns with AS. Try
$users = DB::table('really_long_table_name AS t')
->select('t.id AS uid')
->get();
Let's see it in action with an awesome tinker tool
$ php artisan tinker
[1] > Schema::create('really_long_table_name', function($...
How do HashTables deal with collisions?
...lookups in hash tables very slow.
Option 2: If the hash table entries are all full then the hash table can increase the number of buckets that it has and then redistribute all the elements in the table. The hash function returns an integer and the hash table has to take the result of the hash funct...
Naming convention for Scala constants?
...
The officially recommended style (and I do mean officially) is the first style, camel case with first letter are upper case. It's laid down clearly by Odersky on Programming in Scala.
The style is also followed by the standard library...
A variable modified inside a while loop is not remembered
...
@AvinashYadav The problem isn't really related to while loop or for loop; rather the use of subshell i.e., in cmd1 | cmd2, cmd2 is in a subshell. So if a for loop is executed in a subshell, the unexpected/problematic behaviour will be exhibited.
...
How do I build a numpy array from a generator?
... lists. This is necessary so that space for each item can be consecutively allocated in memory. Consecutive allocation is the key feature of numpy arrays: this combined with native code implementation let operations on them execute much quicker than regular lists.
Keeping this in mind, it is techni...
Is the “struct hack” technically undefined behavior?
...rictly conforming with the C Standard, although it does seem to work under all known implementations. (Compilers which check array bounds carefully might issue warnings.)
The rationale behind the 'strictly conforming' bit is in the spec, section J.2 Undefined behavior, which includes in the list o...