Tutorial by Examples: arg

A method can declare any number of parameters (in this example, i, s and o are the parameters): static void DoSomething(int i, string s, object o) { Console.WriteLine(String.Format("i={0}, s={1}, o={2}", i, s, o)); } Parameters can be used to pass values into a method, so that th...

An iterator method is not executed until the return value is enumerated. It's therefore advantageous to assert preconditions outside of the iterator. public static IEnumerable<int> Count(int start, int count) { // The exception will throw when the method is called, not when the result i...

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...

A decorator takes just one argument: the function to be decorated. There is no way to pass other arguments. But additional arguments are often desired. The trick is then to make a function which takes arbitrary arguments and returns a decorator. Decorator functions def decoratorfactory(message): ...

Finding the minimum/maximum of a sequence of sequences is possible: list_of_tuples = [(0, 10), (1, 15), (2, 8)] min(list_of_tuples) # Output: (0, 10) but if you want to sort by a specific element in each sequence use the key-argument: min(list_of_tuples, key=lambda x: x[0]) # Sorting ...

You can't pass an empty sequence into max or min: min([]) ValueError: min() arg is an empty sequence However, with Python 3, you can pass in the keyword argument default with a value that will be returned if the sequence is empty, instead of raising an exception: max([], default=42) ...

Arguments are defined in parentheses after the function name: def divide(dividend, divisor): # The names of the function and its arguments # The arguments are available by name in the body of the function print(dividend / divisor) The function name and its list of arguments are called...

Optional arguments can be defined by assigning (using =) a default value to the argument-name: def make(action='nothing'): return action Calling this function is possible in 3 different ways: make("fun") # Out: fun make(action="sleep") # Out: sleep # The argumen...

One can give a function as many arguments as one wants, the only fixed rules are that each argument name must be unique and that optional arguments must be after the not-optional ones: def func(value1, value2, optionalvalue=10): return '{0} {1} {2}'.format(value1, value2, optionalvalue1) Wh...

Arbitrary number of positional arguments: Defining a function capable of taking an arbitrary number of arguments can be done by prefixing one of the arguments with a * def func(*args): # args will be a tuple containing all values that are passed in for i in args: print(i) fun...

There is a problem when using optional arguments with a mutable default type (described in Defining a function with optional arguments), which can potentially lead to unexpected behaviour. Explanation This problem arises because a function's default arguments are initialised once, at the point whe...

Direction-Specific Properties CSS allows you to specify a given side to apply margin to. The four properties provided for this purpose are: margin-left margin-right margin-top margin-bottom The following code would apply a margin of 30 pixels to the left side of the selected div. View Resu...

from itertools import imap from future_builtins import map as fmap # Different name to highlight differences image = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] list(map(None, *image)) # Out: [(1, 4, 7), (2, 5, 8), (3, 6, 9)] list(fmap(None, *image)) # Out: [(1, 4, 7), (2, 5, 8),...

The system header TargetConditionals.h defines several macros which you can use from C and Objective-C to determine which platform you're using. #import <TargetConditionals.h> // imported automatically with Foundation - (void)doSomethingPlatformSpecific { #if TARGET_OS_IOS // code t...

5.1 When you take a reference to a method (a property which is a function) in JavaScript, it usually doesn't remember the object it was originally attached to. If the method needs to refer to that object as this it won't be able to, and calling it will probably cause a crash. You can use the .bind...

Supplying pow() with 3 arguments pow(a, b, c) evaluates the modular exponentiation ab mod c: pow(3, 4, 17) # 13 # equivalent unoptimized expression: 3 ** 4 % 17 # 13 # steps: 3 ** 4 # 81 81 % 17 # 13 For built-in types using modular exponentiation is only possible...

When calling a function without an explicit namespace qualifier, the compiler can choose to call a function within a namespace if one of the parameter types to that function is also in that namespace. This is called "Argument Dependent Lookup", or ADL: namespace Test { int call(int i)...

Pull properties from an object passed into a function. This pattern simulates named parameters instead of relying on argument position. let user = { name: 'Jill', age: 33, profession: 'Pilot' } function greeting ({name, profession}) { console.log(`Hello, ${name} the ${pr...

The X-macro approach can be generalized a bit by making the name of the "X" macro an argument of the master macro. This has the advantages of helping to avoid macro name collisions and of allowing use of a general-purpose macro as the "X" macro. As always with X macros, the mas...

Constructors can be created with any kinds of arguments. public class TestClass { private String testData; public TestClass(String testData) { this.testData = testData; } } Called like this: TestClass testClass = new TestClass("Test Data"); A class can ...