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In computer programming, lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed.
The choice of a variable name should be mnemonic — that is, designed to indicate to the casual observer the intent of its use. One-character variable names should be avoided except for temporary "throwaway" variables. Common names for temporary variables are i, j, k, m, and n for integers; c, d, and e for characters. int i;
Python uses the + operator for string concatenation. Python uses the * operator for duplicating a string a specified number of times. The @ infix operator is intended to be used by libraries such as NumPy for matrix multiplication. [104] [105] The syntax :=, called the "walrus operator", was introduced in Python 3.8. It assigns values to ...
Comparison of programming languages; General comparison; Assignment; Basic syntax; Basic instructions; Comments; Control flow Foreach loops; While loops; For loops
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Access modifiers can be given to the instance variable. An instance variable is not a class variable, [4] although there are similarities. Both are a type of class attribute (or class property, field, or data member). While an instance variable's value may differ between instances of a class, a class variable can only have one value at any
The CSV file format is one type of delimiter-separated file format. [2] Delimiters frequently used include the comma, tab, space, and semicolon. Delimiter-separated files are often given a ".csv" extension even when the field separator is not a comma. Many applications or libraries that consume or produce CSV files have options to specify an ...
extension Printable {// All Printable instances will receive this implementation, or they may define their own. func printDetails {print (description)}} // Bool now conforms to Printable, and inherits the printDetails() implementation above. extension Bool: Printable {var description: String {return "An instance of Bool with value: \(self) "}}