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What happens if you call erase() on a map element while iterating from begin to end?
...;
while(pm_it != port_map.end())
{
if (pm_it->second == delete_this_id)
{
pm_it = port_map.erase(pm_it);
}
else
{
++pm_it;
}
}
C++03
Erasing elements in a map does not invalidate any iterators.
(apart from iterators on the element that was deleted)
Actu...
delete_all vs destroy_all?
...ach to delete records from a table. For instance, I have a user whose user ID is across many tables. I want to delete this user and every record that has his ID in all tables.
...
Table header to stay fixed at the top when user scrolls it out of view with jQuery
...ixed position to show the header at the top of the page.
HTML:
<table id="header-fixed"></table>
CSS:
#header-fixed {
position: fixed;
top: 0px; display:none;
background-color:white;
}
JavaScript:
var tableOffset = $("#table-1").offset().top;
var $header = $("#table-1...
How can I find out the current route in Rails?
... always available in params[:controller] and params[:action]. However, outside of it, if you want to recognize the route, this API is not available anymore. It has now shifted to ActionDispatch::Routing and I haven't tried out the recognize_path on it yet.
– Swanand
...
How do I create a custom iOS view class and instantiate multiple copies of it (in IB)?
...t you can construct your interface in IB using a .xib file which is nearly identical to using the storyboard version; You should even be able to copy & paste your views as a whole from your existing interface to the .xib file.
To test this out I created a new empty .xib named "MyCustomTimerView...
How to create a drop shadow only on one side of an element?
...udo element is required.
#box {
background-color: #3D6AA2;
width: 160px;
height: 90px;
position: absolute;
top: calc(10% - 10px);
left: calc(50% - 80px);
}
.box-shadow:after {
content:"";
position:absolute;
width:100%;
bottom:1px;
z-ind...
Android: How to create a Dialog without a title?
I'm trying to generate a custom dialog in Android.
I create my Dialog like this:
25 Answers
...
What is the difference between JOIN and JOIN FETCH when using JPA and Hibernate
...
I use native query with Lazy fetch in both sides of relationship but still loads hierarchy of child relations.
– Badamchi
Dec 25 '19 at 12:18
...
Rails migration: t.references with alternative name?
...n with this:
add_foreign_key :courses, :courses, column: :transferrable_as_id
add_foreign_key :courses, :courses, column: :same_as_id
Update
In Rails 5.1 and above you can add the foreign key in the migration in the create_table block like this:
create_table :courses do |t|
t.string :name
t.ref...
quick random row selection in Postgres
...
You might want to experiment with OFFSET, as in
SELECT myid FROM mytable OFFSET floor(random()*N) LIMIT 1;
The N is the number of rows in mytable. You may need to first do a SELECT COUNT(*) to figure out the value of N.
Update (by Antony Hatchkins)
You must use floor here:
SELE...