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Output Element with Attributes

HTML • Output Element

NSLog Output Format

NSLog(@"NSLog message"); The message that gets printed by calling NSLog has the following format when viewed in Console.app: DateTimeProgram nameProcess IDThread IDMessage2016-07-1608:58:04.681test[46259:1244773]NSLog message

Objective-C Language • Logging

Specifying structure using XPath expressions

SELECT 'XPath example' AS 'head/title', 'This example demonstrates ' AS 'body/p', 'https://www.w3.org/TR/xpath/' AS 'body/p/a/@href', 'XPath expressions' AS 'body/p/a' FOR XML PATH('html') <html> <head> <title>XPath example</title> &...

Microsoft SQL Server • FOR XML PATH

Simulating variable-length lookbehind with \K

Some regex flavors (Perl, PCRE, Oniguruma, Boost) only support fixed-length lookbehinds, but offer the \K feature, which can be used to simulate variable-length lookbehind at the start of a pattern. Upon encountering a \K, the matched text up to this point is discarded, and only the text matching th...

Regular Expressions • Lookahead and Lookbehind

Installing a TypeHandler

The above type handler can be installed into SqlMapper using the AddTypeHandler method. SqlMapper.AddTypeHandler<IHtmlString>(new IHtmlStringTypeHandler()); Type inference allows you to omit the generic type parameter: SqlMapper.AddTypeHandler(new IHtmlStringTypeHandler()); There's als...

Dapper.NET • Type Handlers

String comparison and matching

String comparison uses the == operator between quoted strings. The != operator negates the comparison. if [[ "$string1" == "$string2" ]]; then echo "\$string1 and \$string2 are identical" fi if [[ "$string1" != "$string2" ]]; then echo &quot...

Bash • Conditional Expressions

Creating a map

One can declare and initialize a map in a single statement using a composite literal. Using automatic type Short variable declaration: mapIntInt := map[int]int{10: 100, 20: 100, 30: 1000} mapIntString := map[int]string{10: "foo", 20: "bar", 30: "baz"} mapStringInt :...

Go • Maps

Iterating the elements of a map

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...

Go • Maps

Iterating the keys of a map

people := map[string]int{ "john": 30, "jane": 29, "mark": 11, } for key, _ := range people { fmt.Println("Name:", key) } If you are just looking for the keys, since they are the first value, you can simply drop the underscore: for key := r...

Go • Maps

What is Bool?

Bool is a Boolean type with two possible values: true and false. let aTrueBool = true let aFalseBool = false Bools are used in control-flow statements as conditions. The if statement uses a Boolean condition to determine which block of code to run: func test(_ someBoolean: Bool) { if som...

Swift Language • Booleans

Negate a Bool with the prefix ! operator

The prefix ! operator returns the logical negation of its argument. That is, !true returns false, and !false returns true. print(!true) // prints "false" print(!false) // prints "true" func test(_ someBoolean: Bool) { if !someBoolean { print("someBoolean ...

Swift Language • Booleans

Creating Arrays

Creating immutable arrays: NSArray *myColors = [NSArray arrayWithObjects: @"Red", @"Green", @"Blue", @"Yellow", nil]; // Using the array literal syntax: NSArray *myColors = @[@"Red", @"Green", @"Blue", @"Yellow"]; ...

Objective-C Language • NSArray

Handling Attributes with Different Languages

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"> ...

HTML • Content Languages

Recurse the whole pattern

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>.

Regular Expressions • Recursion

Recurse into a subpattern

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>&...

Regular Expressions • Recursion

Subpattern definitions

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...

Regular Expressions • Recursion

Relative group references

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.

Regular Expressions • Recursion

Using the Delegate Pattern (passing data back)

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...

iOS • Passing Data between View Controllers

Simple method annotation

Documentation comments are placed directly above the method or class they describe. They begin with three forward slashes ///, and allow meta information to be stored via XML. /// <summary> /// Bar method description /// </summary> public void Bar() { } Information in...

C# Language • XML Documentation Comments

Precompiled patterns

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...

Python Language • Regular Expressions (Regex)