Tutorial by Examples: e

4.0 To uppercase $ v="hello" # Just the first character $ printf '%s\n' "${v^}" Hello # All characters $ printf '%s\n' "${v^^}" HELLO # Alternative $ v="hello world" $ declare -u string="$v" $ echo "$string" HELLO WORLD To l...

A lookbehind can be used at the end of a pattern to ensure it ends or not in a certain way. ([a-z ]+|[A-Z ]+)(?<! ) matches sequences of only lowercase or only uppercase words while excluding trailing whitespace.

Ruby offers the expected if and else expressions for branching logic, terminated by the end keyword: # Simulate flipping a coin result = [:heads, :tails].sample if result == :heads puts 'The coin-toss came up "heads"' else puts 'The coin-toss came up "tails"' end ...

In Ruby, there are exactly two values which are considered "falsy", and will return false when tested as a condition for an if expression. They are: nil boolean false All other values are considered "truthy", including: 0 - numeric zero (Integer or otherwise) "&qu...

Number('0') === 0 Number('0') will convert the string ('0') into a number (0) A shorter, but less clear, form: +'0' === 0 The unary + operator does nothing to numbers, but converts anything else to a number. Interestingly, +(-12) === -12. parseInt('0', 10) === 0 parseInt('0', 10) will c...

String(0) === '0' String(0) will convert the number (0) into a string ('0'). A shorter, but less clear, form: '' + 0 === '0'

In most environments, console.table() can be used to display objects and arrays in a tabular format. For example: console.table(['Hello', 'world']); displays like: (index)value0"Hello"1"world" console.table({foo: 'bar', bar: 'baz'}); displays like: (index)value"fo...

If you want to use a pipe character (|) in the content of a cell you'll need to escape it with a backslash. Column | Column ------ | ------ \| Cell \|| \| Cell \| This results in the following table: ColumnColumn| Cell || Cell |

When ASP.NET handles a request, a thread is assigned from the thread pool and a request context is created. The request context contains information about the current request which can be accessed through the static HttpContext.Current property. The request context for the request is then assigned t...

Most browsers support using color keywords to specify a color. For example, to set the color of an element to blue, use the blue keyword: .some-class { color: blue; } CSS keywords are not case sensitive—blue, Blue and BLUE will all result in #0000FF. Color Keywords Color nameHex valueRGB...

Background CSS colors may also be represented as a hex triplet, where the members represent the red, green and blue components of a color. Each of these values represents a number in the range of 00 to FF, or 0 to 255 in decimal notation. Uppercase and/or lowercase Hexidecimal values may be used (i...

currentColor returns the computed color value of the current element. Use in same element Here currentColor evaluates to red since the color property is set to red: div { color: red; border: 5px solid currentColor; box-shadow: 0 0 5px currentColor; } In this case, specifyin...

The Edges The browser creates a rectangle for each element in the HTML document. The Box Model describes how the padding, border, and margin are added to the content to create this rectangle. Diagram from CSS2.2 Working Draft The perimeter of each of the four areas is called an edge. Each edge ...

The Problem The abstract equality and inequality operators (== and !=) convert their operands if the operand types do not match. This type coercion is a common source of confusion about the results of these operators, in particular, these operators aren't always transitive as one would expect. &...

The @property decorator can be used to define methods in a class which act like attributes. One example where this can be useful is when exposing information which may require an initial (expensive) lookup and simple retrieval thereafter. Given some module foobar.py: class Foo(object): def __...

In jQuery you can select elements in a page using many various properties of the element, including: Type Class ID Possession of Attribute Attribute Value Indexed Selector Pseudo-state If you know CSS selectors you will notice selectors in jQuery are the same (with minor exceptions). Ta...

InterruptedException is a confusing beast - it shows up in seemingly innocuous methods like Thread.sleep(), but handling it incorrectly leads to hard-to-manage code that behaves poorly in concurrent environments. At its most basic, if an InterruptedException is caught it means someone, somewhere, c...

If you want to use @property to implement custom behavior for setting and getting, use this pattern: class Cash(object): def __init__(self, value): self.value = value @property def formatted(self): return '${:.2f}'.format(self.value) @formatted.setter def ...

SELECT your_columns, COUNT(*) OVER() as Ttl_Rows FROM your_data_set idnameTtl_Rows1example52foo53bar54baz55quux5 Instead of using two queries to get a count then the line, you can use an aggregate as a window function and use the full result set as the window. This can be used as a base for fur...

Let's say I have this data: Table items idnametag1exampleunique_tag2foosimple42barsimple3bazhello51quuxworld I'd like to get all those lines and know if a tag is used by other lines SELECT id, name, tag, COUNT(*) OVER (PARTITION BY tag) > 1 AS flag FROM items The result will be: idnametag...