Tutorial by Examples: ti

The map function is the simplest one among Python built-ins used for functional programming. map() applies a specified function to each element in an iterable: names = ['Fred', 'Wilma', 'Barney'] Python 3.x3.0 map(len, names) # map in Python 3.x is a class; its instances are iterable # Out: &...

The addition operator (+) adds numbers. var a = 9, b = 3, c = a + b; c will now be 12 This operand can also be used multiple times in a single assignment: var a = 9, b = 3, c = 8, d = a + b + c; d will now be 20. Both operands are converted to primitive types. ...

The subtraction operator (-) subtracts numbers. var a = 9; var b = 3; var c = a - b; c will now be 6 If a string or boolean is provided in place of a number value, it gets converted to a number before the difference is calculated (0 for false, 1 for true): "5" - 1; // 4 7 - ...

The multiplication operator (*) perform arithmetic multiplication on numbers (literals or variables). console.log( 3 * 5); // 15 console.log(-3 * 5); // -15 console.log( 3 * -5); // -15 console.log(-3 * -5); // 15

The Increment operator (++) increments its operand by one. If used as a postfix, then it returns the value before incrementing. If used as a prefix, then it returns the value after incrementing. //postfix var a = 5, // 5 b = a++, // 5 c = a // 6 In this case, a is incr...

The decrement operator (--) decrements numbers by one. If used as a postfix to n, the operator returns the current n and then assigns the decremented the value. If used as a prefix to n, the operator assigns the decremented n and then returns the changed value. var a = 5, // 5 b = a...

Exponentiation makes the second operand the power of the first operand (ab). var a = 2, b = 3, c = Math.pow(a, b); c will now be 8 6 Stage 3 ES2016 (ECMAScript 7) Proposal: let a = 2, b = 3, c = a ** b; c will now be 8 Use Math.pow to find the nth root of a number....

Given a list comprehension you can append one or more if conditions to filter values. [<expression> for <element> in <iterable> if <condition>] For each <element> in <iterable>; if <condition> evaluates to True, add <expression> (usually a function...

An array can be initialized empty: // An empty array $foo = array(); // Shorthand notation available since PHP 5.4 $foo = []; An array can be initialized and preset with values: // Creates a simple array with three strings $fruit = array('apples', 'pears', 'oranges'); // Shorthand no...

print_r() - Outputting Arrays and Objects for debugging print_r will output a human readable format of an array or object. You may have a variable that is an array or object. Trying to output it with an echo will throw the error: Notice: Array to string conversion. You can instead use the print_r...

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...

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 ...

When both operands are numeric, they are compared normally: 1 < 2 // true 2 <= 2 // true 3 >= 5 // false true < false // false (implicitly converted to numbers, 1 > 0) When both operands are strings, they are compared lexicographically (according to alphabeti...

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"

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...

An enum provides a set of related values: enum Direction { case up case down case left case right } enum Direction { case up, down, left, right } Enum values can be used by their fully-qualified name, but you can omit the type name when it can be inferred: let dir = Dire...