Tutorial by Examples: boolean



A boolean can store one of two values, either true or false boolean foo = true; System.out.println("foo = " + foo); // foo = true boolean bar = false; System.out.println("bar = " + bar); // bar = false boolean notFoo = !foo; System.out.prin...
var x = true, y = false; AND This operator will return true if both of the expressions evaluate to true. This boolean operator will employ short-circuiting and will not evaluate y if x evaluates to false. x && y; This will return false, because y is false. OR This operator wil...
Logical OR (||), reading left to right, will evaluate to the first truthy value. If no truthy value is found, the last value is returned. var a = 'hello' || ''; // a = 'hello' var b = '' || []; // b = [] var c = '' || undefined; // c = undefined var d = 1 |...
The searched CASE returns results when a boolean expression is TRUE. (This differs from the simple case, which can only check for equivalency with an input.) SELECT Id, ItemId, Price, CASE WHEN Price < 10 THEN 'CHEAP' WHEN Price < 20 THEN 'AFFORDABLE' ELSE 'EXPENSIVE' E...
The and-operator (&&) and the or-operator (||) employ short-circuiting to prevent unnecessary work if the outcome of the operation does not change with the extra work. In x && y, y will not be evaluated if x evaluates to false, because the whole expression is guaranteed to be false....
Boolean is a type, having two values, denoted as true or false. This code sets the value of $foo as true and $bar as false: $foo = true; $bar = false; true and false are not case sensitive, so TRUE and FALSE can be used as well, even FaLsE is possible. Using lower case is most common and recom...
Due to auto unboxing, one can use a Boolean in an if statement: Boolean a = Boolean.TRUE; if (a) { // a gets converted to boolean System.out.println("It works!"); } That works for while, do while and the condition in the for statements as well. Note that, if the Boolean is null...
The OR (||) operator returns true if one of its two operands evaluates to true, otherwise it returns false. For example, the following code evaluates to true because at least one of the expressions either side of the OR operator is true: if (10 < 20) || (20 < 10) { print("Expression...
Boolean(0) === false Boolean(0) will convert the number 0 into a boolean false. A shorter, but less clear, form: !!0 === false
To convert a string to boolean use Boolean(myString) or the shorter but less clear form !!myString All strings except the empty string (of length zero) are evaluated to true as booleans. Boolean('') === false // is true Boolean("") === false // is true Boolean('0') === fals...
Boolean(...) will convert any data type into either true or false. Boolean("true") === true Boolean("false") === true Boolean(-1) === true Boolean(1) === true Boolean(0) === false Boolean("") === false Boolean("1") === true Boolean("0") === t...
When you use or, it will either return the first value in the expression if it's true, else it will blindly return the second value. I.e. or is equivalent to: def or_(a, b): if a: return a else: return b For and, it will return its first value if it's false, else it r...
Define: module.config(['$urlMatcherFactoryProvider', function($urlMatcherFactory) { $urlMatcherFactory.type('boolean', { decode: function(val) { return val == true || val == "true" }, encode: function(val) { return val ? 1 : 0; }, equals: function(a, b) { return this.is(...
arr = np.arange(7) print(arr) # Out: array([0, 1, 2, 3, 4, 5, 6]) Comparison with a scalar returns a boolean array: arr > 4 # Out: array([False, False, False, False, False, True, True], dtype=bool) This array can be used in indexing to select only the numbers greater than 4: arr[arr&...
One can select rows and columns of a dataframe using boolean arrays. import pandas as pd import numpy as np np.random.seed(5) df = pd.DataFrame(np.random.randint(100, size=(5, 5)), columns = list("ABCDE"), index = ["R" + str(i) for i in range(5)]) print (...
Boolean logic expressions, in addition to evaluating to True or False, return the value that was interpreted as True or False. It is Pythonic way to represent logic that might otherwise require an if-else test. And operator The and operator evaluates all expressions and returns the last expressi...
This example hides the red box (border) if the checkbox is not checked by making use of an IValueConverter. Note: The BooleanToVisibilityConverter used in the example below is a built-in value converter, located in the System.Windows.Controls namespace. XAML: <Window x:Class="StackOverflo...
+firstname:john +surname:doe Matches documents where firstname is john and surname is doe. + predix indicates that the search term must occur (AND). +firstname:john -surname:doe Matches documents where firstname is john and surname is not doe. - predix indicates that the search term must not occu...
There are two kinds of boolean operators in Elixir: boolean operators (they expect either true or false as their first argument) x or y # true if x is true, otherwise y x and y # false if x is false, otherwise y not x # false if x is true, otherwise true All of booleans...
var_dump(filter_var(true, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); // true var_dump(filter_var(false, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); // false var_dump(filter_var(1, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); // true var_dump(filter_var(0, FILTER_VALIDATE_BOOL...

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