A unique index prevents the insertion of duplicated data in a table. NULL values can be inserted in the columns that form part of the unique index (since, by definition, a NULL value is different from any other value, including another NULL value)
-- Creates a unique index for column 'name' in tabl...
Defining a member block inside a resource creates a route that can act on an individual member of that resource-based route:
resources :posts do
member do
get 'preview'
end
end
This generates the following member route:
get '/posts/:id/preview', to: 'posts#preview'
# preview_post_p...
The specifier override has a special meaning in C++11 onwards, if appended at the end of function signature. This signifies that a function is
Overriding the function present in base class &
The Base class function is virtual
There is no run time significance of this specifier as is mainl...
child.py
import time
def main():
print "starting work"
time.sleep(1)
print "work work work work work"
time.sleep(1)
print "done working"
if __name__ == '__main__':
main()
parent.py
import os
def main():
for i in range(5):...
This example starts Notepad, waits for it to be closed, then gets its exit code.
#include <Windows.h>
int main()
{
STARTUPINFOW si = { 0 };
si.cb = sizeof(si);
PROCESS_INFORMATION pi = { 0 };
// Create the child process
BOOL success = CreateProcessW(
L"C:...
Get all ice cream cones that were ordered by people liking chocolate:
IceCream.objects.filter(metadata__buyer__favorite_flavor='chocolate')
See the note in the "Remarks" section about chaining queries.
Removing a variable name from the scope using del v, or removing an object from a collection using del v[item] or del[i:j], or removing an attribute using del v.name, or any other way of removing references to an object, does not trigger any destructor calls or any memory being freed in and of itsel...
Inventory is the Ansible way to track all the systems in your infrastructure. Here is a simple inventory file containing a single system and the login credentials for Ansible.
[targethost]
192.168.1.1 ansible_user=mrtuovinen ansible_ssh_pass=PassW0rd
This example creates a new file named "NewFile.txt", then writes "Hello World!" to its body. If the file already exists, CreateFile will fail and no data will be written.
See the dwCreationDisposition parameter in the CreateFile documentation if you don't want the function to fa...
To get basic information about a DataFrame including the column names and datatypes:
import pandas as pd
df = pd.DataFrame({'integers': [1, 2, 3],
'floats': [1.5, 2.5, 3],
'text': ['a', 'b', 'c'],
'ints with None': [1, None, 3]})
...
End a line with two or more spaces to create a line break.
Ending a line with no spaces
or with just one space
doesn't create a line beak.
Use two or more spaces
to create a line break.
Use an empty line to make a new paragraph.
Ending a line with no spaces
or with just one space...
When adding indented code blocks inside a list you first need a blank line, then to indent the code further. Different flavours of Markdown have different rules for this.
StackExchange requires code to be indented by 8 characters instead of the usual 4. (Spaces replaced with * for clarity):
1...
Examine the following strings:
foobarfoo
bar
foobar
barfoo
the regular expression bar will match all four strings,
\bbar\b will only match the 2nd,
bar\b will be able to match the 2nd and 3rd strings, and
\bbar will match the 2nd and 4th strings.
First of all, we need to add our first Fragment at the beginning, we should do it in the onCreate() method of our Activity:
if (null == savedInstanceState) {
getSupportFragmentManager().beginTransaction()
.addToBackStack("fragmentA")
.replace(R.id.container, FragmentA.n...
