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Variables can be incremented or decremented by 1 using the ++ and -- operators, respectively. When the ++ and -- operators follow variables, they are called post-increment and post-decrement respectively. int a = 10; a++; // a now equals 11 a--; // a now equals 10 again When the ++ and -- ope...

A single case in a switch statement can match on multiple values. let number = 3 switch number { case 1, 2: print("One or Two!") case 3: print("Three!") case 4, 5, 6: print("Four, Five or Six!") default: print("Not One, Two, Three, Four, F...

A single case in a switch statement can match a range of values. let number = 20 switch number { case 0: print("Zero") case 1..<10: print("Between One and Ten") case 10..<20: print("Between Ten and Twenty") case 20..<30: print("Be...

It is often necessary to generate a new array based on the values of an existing array. For example, to generate an array of string lengths from an array of strings: 5.1 ['one', 'two', 'three', 'four'].map(function(value, index, arr) { return value.length; }); // → [3, 3, 5, 4] 6 ['one...

Python lists are zero-indexed, and act like arrays in other languages. lst = [1, 2, 3, 4] lst[0] # 1 lst[1] # 2 Attempting to access an index outside the bounds of the list will raise an IndexError. lst[4] # IndexError: list index out of range Negative indices are interpreted as countin...

dictionary = {"Hello": 1234, "World": 5678} print(dictionary["Hello"]) The above code will print 1234. The string "Hello" in this example is called a key. It is used to lookup a value in the dict by placing the key in square brackets. The number 1234 is ...

Arguments are passed to the program in a manner similar to most C-style languages. $argc is an integer containing the number of arguments including the program name, and $argv is an array containing arguments to the program. The first element of $argv is the name of the program. #!/usr/bin/php p...

When run from the CLI, the constants STDIN, STDOUT, and STDERR are predefined. These constants are file handles, and can be considered equivalent to the results of running the following commands: STDIN = fopen("php://stdin", "r"); STDOUT = fopen("php://stdout", "...

Operator != is the inverse of the == operator. Will return true if the operands aren't equal. The javascript engine will try and convert both operands to matching types if they aren't of the same type. Note: if the two operands have different internal references in memory, then false will be ret...

Place this code in a file named HelloWorld.scala: object Hello { def main(args: Array[String]): Unit = { println("Hello World!") } } Live demo To compile it to bytecode that is executable by the JVM: $ scalac HelloWorld.scala To run it: $ scala Hello When the Scala...

The filter() method creates an array filled with all array elements that pass a test provided as a function. 5.1 [1, 2, 3, 4, 5].filter(function(value, index, arr) { return value > 2; }); 6 [1, 2, 3, 4, 5].filter(value => value > 2); Results in a new array: [3, 4, 5] Fi...

Program options can be handled with the getopt() function. It operates with a similar syntax to the POSIX getopt command, with additional support for GNU-style long options. #!/usr/bin/php // a single colon indicates the option takes a value // a double colon indicates the value may be omitted ...

To iterate through a list you can use for: for x in ['one', 'two', 'three', 'four']: print(x) This will print out the elements of the list: one two three four The range function generates numbers which are also often used in a for loop. for x in range(1, 6): print(x) The res...

123.5.to_s #=> "123.5" String(123.5) #=> "123.5" Usually, String() will just call #to_s. Methods Kernel#sprintf and String#% behave similar to C: sprintf("%s", 123.5) #=> "123.5" "%s" % 123.5 #=> "123.5" "%d&quot...

"123.50".to_i #=> 123 Integer("123.50") #=> 123 A string will take the value of any integer at its start, but will not take integers from anywhere else: "123-foo".to_i # => 123 "foo-123".to_i # => 0 However, there is a difference when ...

"123.50".to_f #=> 123.5 Float("123.50") #=> 123.5 However, there is a difference when the string is not a valid Float: "something".to_f #=> 0.0 Float("something") # ArgumentError: invalid value for Float(): "something"

1/2 #=> 0 Since we are dividing two integers, the result is an integer. To solve this problem, we need to cast at least one of those to Float: 1.0 / 2 #=> 0.5 1.to_f / 2 #=> 0.5 1 / Float(2) #=> 0.5 Alternatively, fdiv may be used to return the floating point result of di...

Consider a database with the following two tables. Employees table: IdFNameLNameDeptId1JamesSmith32JohnJohnson4 Departments table: IdName1Sales2Marketing3Finance4IT Simple select statement * is the wildcard character used to select all available columns in a table. When used as a substitute f...

The JSONSerialization class is built into Apple's Foundation framework. 2.2 Read JSON The JSONObjectWithData function takes NSData, and returns AnyObject. You can use as? to convert the result to your expected type. do { guard let jsonData = "[\"Hello\", \"JSON\"]&q...

Normally, enums can't be recursive (because they would require infinite storage): enum Tree<T> { case leaf(T) case branch(Tree<T>, Tree<T>) // error: recursive enum 'Tree<T>' is not marked 'indirect' } The indirect keyword makes the enum store its payload with...