Tutorial by Examples: g

Routes are defined in config/routes.rb. They are often defined as a group of related routes, using the resources or resource methods. resources :users creates the following seven routes, all mapping to actions of UsersController: get '/users', to: 'users#index' post '/users', ...

Signed integers can be of these types (the int after short, or long is optional): signed char c = 127; /* required to be 1 byte, see remarks for further information. */ signed short int si = 32767; /* required to be at least 16 bits. */ signed int i = 32767; /* required to be at least 16 bits */ ...

A string literal in C is a sequence of chars, terminated by a literal zero. char* str = "hello, world"; /* string literal */ /* string literals can be used to initialize arrays */ char a1[] = "abc"; /* a1 is char[4] holding {'a','b','c','\0'} */ char a2[4] = "abc"...

C99 The header <stdint.h> provides several fixed-width integer type definitions. These types are optional and only provided if the platform has an integer type of the corresponding width, and if the corresponding signed type has a two's complement representation of negative values. See the r...

The C language has three mandatory real floating point types, float, double, and long double. float f = 0.314f; /* suffix f or F denotes type float */ double d = 0.314; /* no suffix denotes double */ long double ld = 0.314l; /* suffix l or L denotes long double */ /* the differen...

Dictionaries are an unordered collection of keys and values. Values relate to unique keys and must be of the same type. When initializing a Dictionary the full syntax is as follows: var books : Dictionary<Int, String> = Dictionary<Int, String>() Although a more concise way of initia...

Add a key and value to a Dictionary var books = [Int: String]() //books = [:] books[5] = "Book 5" //books = [5: "Book 5"] books.updateValue("Book 6", forKey: 5) //[5: "Book 6"] updateValue returns the original value if one exists or nil. let previous...

A value in a Dictionary can be accessed using its key: var books: [Int: String] = [1: "Book 1", 2: "Book 2"] let bookName = books[1] //bookName = "Book 1" The values of a dictionary can be iterated through using the values property: for book in books.values { ...

Swift label.textAlignment = NSTextAlignment.left //or the shorter label.textAlignment = .left Any value in the NSTextAlignment enum is valid: .left, .center, .right, .justified, .natural Objective-C label.textAlignment = NSTextAlignmentLeft; Any value in the NSTextAlignment enum is vali...

Use new Date() to generate a new Date object containing the current date and time. Note that Date() called without arguments is equivalent to new Date(Date.now()). Once you have a date object, you can apply any of the several available methods to extract its properties (e.g. getFullYear() to get t...

Magic (also called dunder as an abbreviation for double-underscore) methods in Python serve a similar purpose to operator overloading in other languages. They allow a class to define its behavior when it is used as an operand in unary or binary operator expressions. They also serve as implementation...

Jsoup can be used to extract links and email address from a webpage, thus "Web email address collector bot" First, this code uses a Regular expression to extract the email addresses, and then uses methods provided by Jsoup to extract the URLs of links on the page. public class JSoupTest {...

After starting a merge, you might want to stop the merge and return everything to its pre-merge state. Use --abort: git merge --abort

This example uses the Cars Table from the Example Databases. UPDATE Cars SET Status = 'READY' This statement will set the 'status' column of all rows of the 'Cars' table to "READY" because it does not have a WHERE clause to filter the set of rows.

This example uses the Cars Table from the Example Databases. UPDATE Cars SET Status = 'READY' WHERE Id = 4 This statement will set the status of the row of 'Cars' with id 4 to "READY". WHERE clause contains a logical expression which is evaluated for each row. If a...

This example uses the Cars Table from the Example Databases. UPDATE Cars SET TotalCost = TotalCost + 100 WHERE Id = 3 or Id = 4 Update operations can include current values in the updated row. In this simple example the TotalCost is incremented by 100 for two rows: The TotalCost of Car #3 i...

The general syntax for declaring a one-dimensional array is type arrName[size]; where type could be any built-in type or user-defined types such as structures, arrName is a user-defined identifier, and size is an integer constant. Declaring an array (an array of 10 int variables in this case) i...

Sometimes it's necessary to set an array to zero, after the initialization has been done. #include <stdlib.h> /* for EXIT_SUCCESS */ #define ARRLEN (10) int main(void) { int array[ARRLEN]; /* Allocated but not initialised, as not defined static or global. */ size_t i; for(i ...

Arrays have fixed lengths that are known within the scope of their declarations. Nevertheless, it is possible and sometimes convenient to calculate array lengths. In particular, this can make code more flexible when the array length is determined automatically from an initializer: int array[] = {...

Accessing array values is generally done through square brackets: int val; int array[10]; /* Setting the value of the fifth element to 5: */ array[4] = 5; /* The above is equal to: */ *(array + 4) = 5; /* Reading the value of the fifth element: */ val = array[4]; As a side effect of...