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JavaScript hashmap equivalent
... three major ways to keep a collection of objects addressable by a key:
Unordered. In this case to retrieve an object by its key we have to go over all keys stopping when we find it. On average it will take n/2 comparisons.
Ordered.
Example #1: a sorted array — doing a binary search we will find...
What's the difference between RANK() and DENSE_RANK() functions in oracle?
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RANK gives you the ranking within your ordered partition. Ties are assigned the same rank, with the next ranking(s) skipped. So, if you have 3 items at rank 2, the next rank listed would be ranked 5.
DENSE_RANK again gives you the ranking within your ordered part...
Programmatically access currency exchange rates [closed]
I'm setting up an online ordering system but I'm in Australia and for international customers I'd like to show prices in US dollars or Euros so they don't have to make the mental effort to convert from Australian dollars.
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What is the advantage of GCC's __builtin_expect in if else statements?
... ...
after_if:
You can see that the instructions are arranged in such an order that the bar case precedes the foo case (as opposed to the C code). This can utilise the CPU pipeline better, since a jump thrashes the already fetched instructions.
Before the jump is executed, the instructions below ...
How to trick an application into thinking its stdout is a terminal, not a pipe
...d a colourful version of git status | less. You need to pass -R to less in order that it respect the colours, and you need to use script to get git status to output colour. But we don't want script to keep ownership of the keyboard, we want this to go to less. So I use this now and it works well: 0&...
Capturing Groups From a Grep RegEx
..."*.jpg"
regex="[0-9]+_([a-z]+)_[0-9a-z]*"
for f in $files # unquoted in order to allow the glob to expand
do
if [[ $f =~ $regex ]]
then
name="${BASH_REMATCH[1]}"
echo "${name}.jpg" # concatenate strings
name="${name}.jpg" # same thing stored in a variable
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“Cross origin requests are only supported for HTTP.” error when loading a local file
... ... the Ruby Gods say this works as well:
ruby -run -e httpd . -p 8080
PHP
Of course PHP also has its solution.
php -S localhost:8000
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Finding the index of an item in a list
...omplexity in list length
An index call checks every element of the list in order, until it finds a match. If your list is long, and you don't know roughly where in the list it occurs, this search could become a bottleneck. In that case, you should consider a different data structure. Note that if yo...
Difference between VARCHAR and TEXT in MySQL [duplicate]
...up to 16 MB, LONGTEXT up to 4 GB. If you use LONGTEXT and get the data via PHP (at least if you use mysqli without store_result), you maybe get a memory allocation error, because PHP tries to allocate 4 GB of memory to be sure the whole string can be buffered. This maybe also happens in other langua...
MongoDB Many-to-Many Association
...f clear then is generally discouraged, but if needed can be implemented by ordering the operations:
Get the list of user names from Role.users.
Iterate the user names from step 1, remove the role name from User.roles.
Clear the Role.users.
In the case of an issue, which is most likely to occur w...