Tutorial by Examples: le

The << operator will perform a bitwise "left shift," where the left operand's value is moved left by the number of bits given by the right operand. # 2 = 0b10 2 << 2 # Out: 8 # 8 = 0b1000 bin(2 << 2) # Out: 0b1000 Performing a left bit shift of 1 is equivalent ...

if [[ $file1 -ef $file2 ]]; then echo "$file1 and $file2 are the same file" fi “Same file” means that modifying one of the files in place affects the other. Two files can be the same even if they have different names, for example if they are hard links, or if they are symbolic links...

if [[ -r $filename ]]; then echo "$filename is a readable file" fi if [[ -w $filename ]]; then echo "$filename is a writable file" fi if [[ -x $filename ]]; then echo "$filename is an executable file" fi These tests take permissions and ownership into a...

The -e conditional operator tests whether a file exists (including all file types: directories, etc.). if [[ -e $filename ]]; then echo "$filename exists" fi There are tests for specific file types as well. if [[ -f $filename ]]; then echo "$filename is a regular file&quot...

import fmt people := map[string]int{ "john": 30, "jane": 29, "mark": 11, } for key, value := range people { fmt.Println("Name:", key, "Age:", value) } Note that when iterating over a map with a range loop, the iteration order i...

The delete built-in function removes the element with the specified key from a map. people := map[string]int{"john": 30, "jane": 29} fmt.Println(people) // map[john:30 jane:29] delete(people, "john") fmt.Println(people) // map[jane:29] If the map is nil or ther...

You shouldn't call NSLog without a literal format string like this: NSLog(variable); // Dangerous code! If the variable is not an NSString, the program will crash, because NSLog expects an NSString. If the variable is an NSString, it will work unless your string contains a %. NSLog will pars...

To create a first-level (<h1>) header, use the equal sign (=) in a line under your text: All About Dogs ============== All About Dogs Use hyphens (-) for second-level (<h2>) headers: The Debut Novel --------------- The Debut Novel The line below the header can be of a...

We can illustrate this problem with the following pseudo-code function foo() { global $bob; $bob->doSomething(); } Your first question here is an obvious one Where did $bob come from? Are you confused? Good. You've just learned why globals are confusing and considered a bad p...

NSArray *myColors = [NSArray arrayWithObjects: @"Red", @"Green", @"Blue", @"Yellow", nil]; NSLog (@"Number of elements in array = %lu", [myColors count]);

NSMutableArray *myColors; myColors = [NSMutableArray arrayWithObjects: @"Red", @"Green", @"Blue", @"Yellow", nil]; [myColors addObject: @"Indigo"]; [myColors addObject: @"Violet"]; //Add objects from an NSArray NSArray *myArray = @[@...

NSMutableArray *myColors; int i; int count; myColors = [NSMutableArray arrayWithObjects: @"Red", @"Green", @"Blue", @"Yellow", nil]; [myColors insertObject: @"Indigo" atIndex: 1]; [myColors insertObject: @"Violet" atIndex: 3];

Remove at specific index: [myColors removeObjectAtIndex: 3]; Remove the first instance of a specific object: [myColors removeObject: @"Red"]; Remove all instances of a specific object: [myColors removeObjectIdenticalTo: @"Red"]; Remove all objects: [myColors removeAl...

NSArray *myColors = @[@"Red", @"Green", @"Blue", @"Yellow"]; // Preceding is the preferred equivalent to [NSArray arrayWithObjects:...] Getting a single item The objectAtIndex: method provides a single object. The first object in an NSArray is index 0. Si...

The lang attribute is used to specify the language of element content and attribute text values: <p lang="en">The content of this element is in English.</p> <p lang="en" title="The value of this attribute is also in English.">The content of this el...

You can "overwrite" a language declaration: <p lang="en">This English sentence contains the German word <span lang="de">Hallo</span>.</p>

The <section> element represents a generic section to thematically group content. Every section, typically, should be able to be identified with a heading element as a child of the section. You can use the <section> element within an <article> and vice-versa. Every section shou...

Object initializers are handy when you need to create an object and set a couple of properties right away, but the available constructors are not sufficient. Say you have a class public class Book { public string Title { get; set; } public string Author { get; set; } // the rest o...

The construct (?R) is equivalent to (?0) (or \g<0>) - it lets you recurse the whole pattern: <(?>[^<>]+|(?R))+> This will match properly balanced angle brackets with any text in-between the brackets, like <a<b>c<d>e>.

To pass data from the current view controller back to the previous view controller, you can use the delegate pattern. This example assumes that you have made a segue in the Interface Builder and that you set the segue identifier to showSecondViewController. The outlets and actions must also be ho...