Tutorial by Examples: f

A NFA (Nondeterministic Finite Automaton) engine is driven by the pattern. Principle The regex pattern is parsed into a tree. The current position pointer is set to the start of the input string, and a match is attempted at this position. If the match fais, the position is incremented to the ne...

A DFA (Deterministic Finite Automaton) engine is driven by the input. Principle The algorithm scans through the input string once, and remembers all possible paths in the regex which could match. For instance, when an alternation is encountered in the pattern, two new paths are created and attem...

Sometimes we have to resize a UILabel based on dynamic content where the text length is unknown. In this example, width of the UILabel is fixed at 280 points and the height is infinite, lets say 9999. Estimating the frame with respect to the text style and maximumLabelSize. Objective-C UILabel * l...

cat >file It will let you write the text on terminal which will be saved in a file named file. cat >>file will do the same, except it will append the text to the end of the file. N.B: Ctrl+D to end writing text on terminal (Linux) A here document can be used to inline the content...

To create a list of constants - assign iota value to each element: const ( a = iota // a = 0 b = iota // b = 1 c = iota // c = 2 ) To create a list of constants in a shortened way - assign iota value to the first element: const ( a = iota // a = 0 b // b = 1 c /...

Because iota is incremented after each ConstSpec, values within the same expression list will have the same value for iota: const ( bit0, mask0 = 1 << iota, 1<<iota - 1 // bit0 == 1, mask0 == 0 bit1, mask1 // bit1 == 2, mask1 == 1 _, _ ...

Iota can be very useful when creating a bitmask. For instance, to represent the state of a network connection which may be secure, authenticated, and/or ready, we might create a bitmask like the following: const ( Secure = 1 << iota // 0b001 Authn // 0b010 Ready ...

Often times, responsive web design involves media queries, which are CSS blocks that are only executed if a condition is satisfied. This is useful for responsive web design because you can use media queries to specify different CSS styles for the mobile version of your website versus the desktop ver...

Changing some CSS attribute will trigger the browser to synchronously calculate the style and layout, which is a bad thing when you need to animate at 60fps. DON'T Animate with left and top trigger layout. #box { left: 0; top: 0; transition: left 0.5s, top 0.5s; position: absolute; ...

If you have a multi-parameter type-class with arguments a, b, c, and x, this extension lets you express that the type x can be uniquely identified from a, b, and c: class SomeClass a b c x | a b c -> x where ... When declaring an instance of such class, it will be checked against all other in...

To setup a new credential profile with the name myprofile: $ aws configure --profile myprofile AWS Access Key ID [None]: ACCESSKEY AWS Secret Access Key [None]: SECRETKEY Default region name [None]: REGIONNAME Default output format [None]: text | table | json For the AWS access key id and se...

There are two ways to define functions with multiple parameters in F#, Curried functions and Tupled functions. let curriedAdd x y = x + y // Signature: x:int -> y:int -> int let tupledAdd (x, y) = x + y // Signature: x:int * y:int -> int All functions defined from outside F# (such as ...

The term 'heap' is a general computing term meaning an area of memory from which portions can be allocated and deallocated independently of the memory provided by the stack. In C++ the Standard refers to this area as the Free Store which is considered a more accurate term. Areas of memory allocate...

A std::string containing a number can be converted into an integer type, or a floating point type, using conversion functions. Note that all of these functions stop parsing the input string as soon as they encounter a non-numeric character, so "123abc" will be converted into 123. The s...

Installing aws cli in Ubuntu / Debian Instance sudo apt-get install -y python-dev python-pip sudo pip install awscli aws --version aws configure Installing aws cli using python Using pip you can install aws cli in windows, OS X and Linux sudo pip install awscli Configuring the AWS Comman...

Unit Test Unit tests are used to ensure that your code has no syntax error and to test the logic of your code to work as what you expected. Quick example: src/AppBundle/Calculator/BillCalculator.php <?php namespace AppBundle\Calculator; use AppBundle\Calculator\TaxCalculator; class Bi...

A subprogram (which defines a procedure), can be either a subroutine or a function; it is said to be an internal subprogram if it is called or invoked from the same program or subprogram that contains it, as follows program my_program ! declarations ! executable statements, ! among which...

A subprogram is said to be external when it is not contained in the main program, nor in a module or antoher subprogram. In particular it can be defined by means of a programming language other than Fortran. When an external subprogram is invoked, the compiler cannot access to its code, so all the ...

Most advanced user interfaces require the user to be able to pass information between the various functions which make up a user interface. MATLAB has a number of different methods to do so. guidata MATLAB's own GUI Development Environment (GUIDE) prefers to use a struct named handles to pass da...

Floating-point numbers cannot represent all real numbers. This is known as floating point inaccuracy. There are infinitely many floating points numbers and they can be infinitely long (e.g. π), thus being able to represent them perfectly would require infinitely amount of memory. Seeing this was a ...