Search results
Results from the WOW.Com Content Network
The Python programming language includes extensive support for creating and manipulating symbol tables. [5] Properties that can be queried include whether a given symbol is a free variable or a bound variable , whether it is block scope or global scope , whether it is imported, and what namespace it belongs to.
Even when using numerical indexes, PHP internally stores arrays as associative arrays. [13] So, PHP can have non-consecutively numerically indexed arrays. The keys have to be of integer (floating point numbers are truncated to integer) or string type, while values can be of arbitrary types, including other arrays and objects.
is how one would use Fortran to create arrays from the even and odd entries of an array. Another common use of vectorized indices is a filtering operation. Consider a clipping operation of a sine wave where amplitudes larger than 0.5 are to be set to 0.5. Using S-Lang, this can be done by y = sin(x); y[where(abs(y)>0.5)] = 0.5;
In other array types, a slice can be replaced by an array of different size, with subsequent elements being renumbered accordingly – as in Python's list assignment A[5:5] = [10,20,30], that inserts three new elements (10, 20, and 30) before element "A[5]". Resizable arrays are conceptually similar to lists, and the two concepts are synonymous ...
An undefined variable in the source code of a computer program is a variable that is accessed in the code but has not been declared by that code. [ 1 ] In some programming languages , an implicit declaration is provided the first time such a variable is encountered at compile time .
In mathematical terms, an associative array is a function with finite domain. [1] It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. [2] The two major solutions to the dictionary problem are hash tables and search trees.
The JS++ programming language is able to analyze if an array index or map key is out-of-bounds at compile time using existent types, which is a nominal type describing whether the index or key is within-bounds or out-of-bounds and guides code generation. Existent types have been shown to add only 1ms overhead to compile times. [2]
For that reason, the elements of an array data structure are required to have the same size and should use the same data representation. The set of valid index tuples and the addresses of the elements (and hence the element addressing formula) are usually, [3] [5] but not always, [2] fixed while the array is in use.