Tutorial by Examples: r

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

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

NSMutableArray *myColors = [NSMutableArray arrayWithObjects: @"red", @"green", @"blue", @"yellow", nil]; NSArray *sortedArray; sortedArray = [myColors sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

Table cells can span multiple columns or rows using the colspan and rowspan attributes. These attributes can be applied to <th> and <td> elements. <table> <tr> <td>row 1 col 1</td> <td>row 1 col 2</td> <td>row 1 c...

You can "overwrite" a parent element's language declaration by introducing any element apart from applet, base, basefont, br, frame, frameset, hr, iframe, meta, param, script (of HTML 4.0) with an own lang attribute: <p lang="en" title="An English paragraph"> ...

From Wikipedia: A test fixture is something used to consistently test some item, device, or piece of software. It can also enhance readability of tests by extracting common initialisation / finalisation code from the test methods themselves. Where common initialisation can be executed once in...

params allows a method parameter to receive a variable number of arguments, i.e. zero, one or multiple arguments are allowed for that parameter. static int AddAll(params int[] numbers) { int total = 0; foreach (int number in numbers) { total += number; } ret...

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>.

You can recurse into a subpattern using the following constructs (depending on the flavor), assuming n is a capturing group number, and name the name of a capturing group. (?n) \g<n> \g'0' (?&name) \g<name> \g'name' (?P>name) The following pattern: \[(?<angle>&...

The (?(DEFINE)...) construct lets you define subpatterns you may reference later through recursion. When encountered in the pattern it will not be matched against. This group should contain named subpattern definitions, which will be accessible only through recursion. You can define grammars this w...

Subpatterns can be referenced with their relative group number: (?-1) will recurse into the previous group (?+1) will recurse into the next group Also usable with the \g<N> syntax.

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...

You can create a horizontal break to divide your text by placing three (or more) underscores ___ or asterisks *** or hyphens --- on their own line. You can create a horizontal break to divide your text by placing three (or more) underscores or asterisks or hyphens o...

import re precompiled_pattern = re.compile(r"(\d+)") matches = precompiled_pattern.search("The answer is 41!") matches.group(1) # Out: 41 matches = precompiled_pattern.search("Or was it 42?") matches.group(1) # Out: 42 Compiling a pattern allows it to be r...

Given the flavors, the named capture group may looks like this: (?'name'X) (?<name>X) (?P<name>X) With X being the pattern you want to capture. Let's consider the following string: Once upon a time there was a pretty little girl... Once upon a time there was a unicorn with an h...

As you may (or not) know, you can reference a capture group with: $1 1 being the group number. In the same way, you can reference a named capture group with: ${name} \{name} g\{name} Let's take the preceding example and replace the matches with The hero of the story is a ${subject}. T...

A reference cycle (or retain cycle) is so named because it indicates a cycle in the object graph: Each arrow indicates one object retaining another (a strong reference). Unless the cycle is broken, the memory for these objects will never be freed. A retain cycle is created when two instances of ...

In a normal string, the backslash character is the escape character, which instructs the compiler to look at the next character(s) to determine the actual character in the string. (Full list of character escapes) In verbatim strings, there are no character escapes (except for "" which is ...

To parse lots of parameters, the prefered way of doing this is using a while loop, a case statement, and shift. shift is used to pop the first parameter in the series, making what used to be $2, now be $1. This is useful for processing arguments one at a time. #!/bin/bash # Load the user define...

These behave in the same manner as nested subqueries but with a different syntax. WITH ReadyCars AS ( SELECT * FROM Cars WHERE Status = 'READY' ) SELECT ID, Model, TotalCost FROM ReadyCars ORDER BY TotalCost; IDModelTotalCost1Ford F-1502002Ford F-150230 Equivalent subquery syntax ...