Tutorial by Examples: ar

If the compiler can infer that an object can't be null at a certain point, you don't have to use the special operators anymore: var string: String? = "Hello!" print(string.length) // Compile error if(string != null) { // The compiler now knows that string can't be null print(...

The unary plus (+) precedes its operand and evaluates to its operand. It attempts to convert the operand to a number, if it isn't already. Syntax: +expression Returns: a Number. Description The unary plus (+) operator is the fastest (and preferred) method of converting something into a n...

The unary negation (-) precedes its operand and negates it, after trying to convert it to number. Syntax: -expression Returns: a Number. Description The unary negation (-) can convert the same types / values as the unary plus (+) operator can. Values that can't be converted will evaluat...

A rank-1 array value can be created using an array constructor, with the syntax (/ ... /) [ ... ] The form [...] was introduced in Fortran 2003 and is generally regarded as clearer to read, especially in complex expressions. This form is used exclusively in this example. The values featuring ...

set(my_global_string "a string value" CACHE STRING "a description about the string variable") set(my_global_bool TRUE CACHE BOOL "a description on the boolean cache entry") In case a cached variable is already defined in the cache when CMake processes the ...

set(my_variable "the value is a string") By default, a local variable is only defined in the current directory and any subdirectories added through the add_subdirectory command. To extend the scope of a variable there are two possibilities: CACHE it, which will make it globally av...

macro(set_my_variable _INPUT) if("${_INPUT}" STREQUAL "Foo") set(my_output_variable "foo") else() set(my_output_variable "bar") endif() endmacro(set_my_variable) Use the macro: set_my_variable("Foo") message(STATUS ${my_outpu...

macro(set_custom_variable _OUT_VAR) set(${_OUT_VAR} "Foo") endmacro(set_custom_variable) Use it with set_custom_variable(my_foo) message(STATUS ${my_foo}) which will print -- Foo

interface ITable { // an indexer can be declared in an interface object this[int x, int y] { get; set; } } class DataTable : ITable { private object[,] cells = new object[10, 10]; /// <summary> /// implementation of the indexer declared in the interface //...

To destroy, delete, or unset an array: unset array To destroy, delete, or unset a single array element: unset array[10]

4.0 Declare an associative array declare -A aa Declaring an associative array before initialization or use is mandatory. Initialize elements You can initialize elements one at a time as follows: aa[hello]=world aa[ab]=cd aa["key with space"]="hello world" You can al...

Arithmetic if statement allows one to use three branches depending on the result of an arithmetic expression if (arith_expr) label1, label2, label3 This if statement transfers control flow to one of the labels in a code. If the result of arith_expr is negative label1 is involved, if the result i...

You can create parser error messages according to your script needs. This is through the argparse.ArgumentParser.error function. The below example shows the script printing a usage and an error message to stderr when --foo is given but not --bar. import argparse parser = argparse.ArgumentParser...

First: The path structure If you don't have it you need to create the middleware folder within your app following the structure: yourproject/yourapp/middleware The folder middleware should be placed in the same folder as settings.py, urls, templates... Important: Don't forget to create the ini...

Using parse_line() of Text::ParseWords: use 5.010; use Text::ParseWords; my $line = q{"a quoted, comma", word1, word2}; my @parsed = parse_line(',', 1, $line); say for @parsed; Output: "a quoted, comma" word1 word2

Similar to the built-in function zip(), itertools.zip_longest will continue iterating beyond the end of the shorter of two iterables. from itertools import zip_longest a = [i for i in range(5)] # Length is 5 b = ['a', 'b', 'c', 'd', 'e', 'f', 'g'] # Length is 7 for i in zip_longest(a, b): x...

Visual Basic has Left, Right, and Mid functions that returns characters from the Left, Right, and Middle of a string. These methods does not exist in C#, but can be implemented with Substring(). They can be implemented as an extension methods like the following: public static class StringExtens...

explode and strstr are simpler methods to get substrings by separators. A string containing several parts of text that are separated by a common character can be split into parts with the explode function. $fruits = "apple,pear,grapefruit,cherry"; print_r(explode(",",$fruits))...

The most flexible ways to sort an array is with the sortedArrayUsingComparator: method. This accepts an ^NSComparisonResult(id obj1, id obj2) block. Return Value Description NSOrderedAscending obj1 comes before obj2 NSOrderedSame obj1 and obj2 have no order NSOrdere...

(defun foobar (x y) (format t "X: ~s~@ Y: ~s~%" x y)) (foobar 10 20) ; X: 10 ; Y: 20 ;=> NIL