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The new operator can be used to create an object wrapper for a Boolean primitive. However, the typeof operator does not return boolean for the object wrapper, it returns object. Because all objects evaluate as true, a method such as .valueOf(), or .toString(), must be used to retrieve the wrapped value.
An invocation of gethash actually returns two values: the value or substitute value for the key and a boolean indicator, returning T if the hash table contains the key and NIL to signal its absence. ( multiple-value-bind ( value contains-key ) ( gethash "Sally Smart" phone-book ) ( if contains-key ( format T "~&The associated value is: ~s ...
String functions are used in computer programming languages to manipulate a string or query information about a string (some do both).. Most programming languages that have a string datatype will have some string functions although there may be other low-level ways within each language to handle strings directly.
Most contemporary type systems go beyond JavaScript's simple type "function object" and have a family of function types differentiated by argument and return types, such as the type Int -> Bool denoting functions taking an integer and returning a Boolean. In C, a function is not a first-class data type but function pointers can be manipulated ...
The Function constructor can be used to trigger execution of JavaScript code contained in a string as if it were native JavaScript. So, for example, the statement alert() is equivalent to Function("alert()")() .
That is, it returns the true, original type of the object, irrespective of any type casting. In these languages, the typeof operator is the method for obtaining run-time type information . In other languages, such as C# [ 2 ] or D [ 3 ] and, to some degree, in C (as part of nonstandard extensions and proposed standard revisions ), [ 4 ] [ 5 ...
In contrast, converting between Booleans and integers (or any other types) still required explicit tests or function calls, as in ALGOL 60. This approach (Boolean is an enumerated type) was adopted by most later languages which had enumerated types, such as Modula, Ada, and Haskell.
In C and C++ arrays do not support the size function, so programmers often have to declare separate variable to hold the size, and pass it to procedures as a separate parameter. Elements of a newly created array may have undefined values (as in C), or may be defined to have a specific "default" value such as 0 or a null pointer (as in Java).