Tutorial by Examples: c

string strCmdText = "/C copy /b Image1.jpg + Archive.rar Image2.jpg"; System.Diagnostics.Process.Start("CMD.exe",strCmdText); This is to hide the cmd window. System.Diagnostics.Process process = new System.Diagnostics.Process(); System.Diagnostics.ProcessStartInfo startInfo...

Reducing a list to a single value is easy when you have _.reduce. Let's say we wanted to see if a group of people could afford a cab ride. We'd want to look at all the money they have together as a group, which means we'd want to reduce a list of objects to a single value, in this case the sum ...

A minimal Dockerfile looks like this: FROM alpine CMD ["echo", "Hello StackOverflow!"] This will instruct Docker to build an image based on Alpine (FROM), a minimal distribution for containers, and to run a specific command (CMD) when executing the resulting image. Build an...

To copy files from the build context in a Docker image, use the COPY instruction: COPY localfile.txt containerfile.txt If the filename contains spaces, use the alternate syntax: COPY ["local file", "container file"] The COPY command supports wildcards. It can be used for ...

Group common operations Docker builds images as a collection of layers. Each layer can only add data, even if this data says that a file has been deleted. Every instruction creates a new layer. For example: RUN apt-get -qq update RUN apt-get -qq install some-package Has a couple of downsides: ...

_mycompletion() { local command_name="$1" # not used in this example local current_word="$2" local previous_word="$3" # not used in this example # COMPREPLY is an array which has to be filled with the possible completions # compgen is used to fi...

It is possible to save a Docker container's filesystem contents to a tarball archive file. This is useful in a pinch for moving container filesystems to different hosts, for example if a database container has important changes and it isn't otherwise possible to replicate those changes elsewhere. Pl...

Let's swap the implementation of methodOne() and methodTwo() in our TestSwizzling class: class TestSwizzling : NSObject { dynamic func methodOne()->Int{ return 1 } } extension TestSwizzling { //In Objective-C you'd perform the swizzling in load(), //but t...

import fileinput replacements = {'Search1': 'Replace1', 'Search2': 'Replace2'} for line in fileinput.input('filename.txt', inplace=True): for search_for in replacements: replace_with = replacements[search_for] line = line.replace(search_for, replace_with...

The method compareTo should be used to compare BigDecimals: BigDecimal a = new BigDecimal(5); a.compareTo(new BigDecimal(0)); // a is greater, returns 1 a.compareTo(new BigDecimal(5)); // a is equal, returns 0 a.compareTo(new BigDecimal(10)); // a is less, returns -1 Commonly you shou...

GCD provides mechanism for performing a loop, whereby the loops happen concurrently with respect to each other. This is very useful when performing a series of computationally expensive calculations. Consider this loop: for index in 0 ..< iterations { // Do something computationally expens...

A powerful alternative to virtualenv is Anaconda - a cross-platform, pip-like package manager bundled with features for quickly making and removing virtual environments. After installing Anaconda, here are some commands to get started: Create an environment conda create --name <envname> pyth...

Applying a function to a collection/stream and creating a new collection/stream is called a projection. /// Projection var newReleases = [ [ "id": 70111470, "title": "Die Hard", "boxart": "http://cdn-0.nflximg.com/images...

A HAVING clause filters the results of a GROUP BY expression. Note: The following examples are using the Library example database. Examples: Return all authors that wrote more than one book (live example). SELECT a.Id, a.Name, COUNT(*) BooksWritten FROM BooksAuthors ba INNER JOIN Aut...

We can use 1,2,3.. to determine the type of order: SELECT * FROM DEPT ORDER BY CASE DEPARTMENT WHEN 'MARKETING' THEN 1 WHEN 'SALES' THEN 2 WHEN 'RESEARCH' THEN 3 WHEN 'INNOVATION' THEN 4 ELSE 5 END, CITY IDREGIONCITYDEPARTMENTEMPLOYEES_N...

PostgreSQL and SQLite To create a temporary table local to the session: CREATE TEMP TABLE MyTable(...); SQL Server To create a temporary table local to the session: CREATE TABLE #TempPhysical(...); To create a temporary table visible to everyone: CREATE TABLE ##TempPhysicalVisibleToEveryo...

When results need to have some logic applied 'on the fly' one can use CASE statement to implement it. SELECT CASE WHEN Col1 < 50 THEN 'under' ELSE 'over' END threshold FROM TableName also can be chained SELECT CASE WHEN Col1 < 50 THEN 'under' WHEN Col1 > 50 AND Col1 ...

Sometimes when tables are used mostly (or only) for reads, indexing does not help anymore and every little bit counts, one might use selects without LOCK to improve performance. SQL Server SELECT * FROM TableName WITH (nolock) MySQL SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;...

Sometimes one wants to capture the records that have just been updated. CREATE TABLE #TempUpdated(ID INT) Update TableName SET Col1 = 42 OUTPUT inserted.ID INTO #TempUpdated WHERE Id > 50

WITH cte AS ( SELECT ProjectID, ROW_NUMBER() OVER (PARTITION BY ProjectID ORDER BY InsertDate DESC) AS rn FROM ProjectNotes ) DELETE FROM cte WHERE rn > 1;