Tutorial by Examples: en

Maps in go are not safe for concurrency. You must take a lock to read and write on them if you will be accessing them concurrently. Usually the best option is to use sync.RWMutex because you can have read and write locks. However, a sync.Mutex could also be used. type RWMap struct { sync.RWMut...

Variable declaration for examples: Collection<String> abc = Arrays.asList("a", "b", "c"); Collection<String> digits = Arrays.asList("1", "2", "3"); Collection<String> greekAbc = Arrays.asList("alpha", "be...

Two Arrays var array1 = [1, 2]; var array2 = [3, 4, 5]; 3 var array3 = array1.concat(array2); // returns a new array 6 var array3 = [...array1, ...array2] Results in a new Array: [1, 2, 3, 4, 5] Multiple Arrays var array1 = ["a", "b"], array2 = ["...

Unshift Use .unshift to add one or more items in the beginning of an array. For example: var array = [3, 4, 5, 6]; array.unshift(1, 2); array results in: [1, 2, 3, 4, 5, 6] Push Further .push is used to add items after the last currently existent item. For example: var array = [1, 2, 3...

Given the following array var array = [ ["key1", 10], ["key2", 3], ["key3", 40], ["key4", 20] ]; You can sort it sort it by number(second index) array.sort(function(a, b) { return a[1] - b[1]; }) 6 array.sort((a,b) => a[1] - b[1]);...

Simple arithmetic: $var = 1 # Assignment. Sets the value of a variable to the specified value $var += 2 # Addition. Increases the value of a variable by the specified value $var -= 1 # Subtraction. Decreases the value of a variable by the specified value $var *= 2 # Multiplicati...

Python 2.x2.6 The format() method can be used to change the alignment of the string. You have to do it with a format expression of the form :[fill_char][align_operator][width] where align_operator is one of: < forces the field to be left-aligned within width. > forces the field to be righ...

#include <stdio.h> /* for perror(), fopen(), fputs() and fclose() */ #include <stdlib.h> /* for the EXIT_* macros */ int main(int argc, char **argv) { int e = EXIT_SUCCESS; /* Get path from argument to main else default to output.txt */ char *path = (argc > 1...

Library cargo new my-library This creates a new directory called my-library containing the cargo config file and a source directory containing a single Rust source file: my-library/Cargo.toml my-library/src/lib.rs These two files will already contain the basic skeleton of a library, such th...

CommandDescriptionaAppend text following current cursor positionAAppend text at the end of current lineiInsert text before the current cursor positionIInsert text before first non-blank character of current linegIInsert text in first column of cursor linegiInsert text at same position where it was l...

To run migrations in the test environment, run this shell command: rake db:migrate RAILS_ENV=test 5.0 Starting in Rails 5.0, you can use rails instead of rake: rails db:migrate RAILS_ENV=test

To add a reference to a team to the users table, run this command: $ rails generate migration AddTeamRefToUsers team:references This generates the following migration: class AddTeamRefToUsers < ActiveRecord::Migration[5.0] def change add_reference :users, :team, foreign_key: true ...

Use the : operator to create sequences of numbers, such as for use in vectorizing larger chunks of your code: x <- 1:5 x ## [1] 1 2 3 4 5 This works both ways 10:4 # [1] 10 9 8 7 6 5 4 and even with floating point numbers 1.25:5 # [1] 1.25 2.25 3.25 4.25 or negatives -4:4 ...

Say you want to perform in action (in this case, logging "Foo"), while doing something else (logging "Bar"). Normally, if you don't use concurrency, one of these actions is going to be fully executed, and the other run will run only after it's completely finished. But with concur...

Ruby uses the case keyword for switch statements. As per the Ruby Docs: Case statements consist of an optional condition, which is in the position of an argument to case, and zero or more when clauses. The first when clause to match the condition (or to evaluate to Boolean truth, if the condi...

c := exec.Command(name, arg...) b := &bytes.Buffer{} c.Stdout = b c.Stdin = stdin if err := c.Start(); err != nil { return nil, err } timedOut := false intTimer := time.AfterFunc(timeout, func() { log.Printf("Process taking too long. Interrupting: %s %s", name, strings...

cmd := exec.Command("sleep", "5") // Does not wait for command to complete before returning err := cmd.Start() if err != nil { log.Fatal(err) } // Wait for cmd to Return err = cmd.Wait() log.Printf("Command finished with error: %v", err)

If you want to add custom.js script that is located in the js/ folder of your theme, you'll need to enqueue it. In functions.php add <?php add_action( 'after_setup_theme', 'yourtheme_theme_setup' ); if ( ! function_exists( 'yourtheme_theme_setup' ) ) { function yourtheme_theme_setup()...

When a column name matches a reserved keyword, standard SQL requires that you enclose it in double quotation marks: SELECT "ORDER", ID FROM ORDERS Note that it makes the column name case-sensitive. Some DBMSes have proprietary ways of quoting names. For example, SQL Serve...

Some convenience functions to manipulate data.frames are subset(), transform(), with() and within(). subset The subset() function allows you to subset a data.frame in a more convenient way (subset also works with other classes): subset(mtcars, subset = cyl == 6, select = c("mpg", "...