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In PL/I the original term for a union was cell, [5] which is still accepted as a synonym for union by several compilers. The union declaration is similar to the structure definition, where elements at the same level within the union declaration occupy the same storage. Elements of the union can be any data type, including structures and array.
In addition to support for vectorized arithmetic and relational operations, these languages also vectorize common mathematical functions such as sine. For example, if x is an array, then y = sin (x) will result in an array y whose elements are sine of the corresponding elements of the array x. Vectorized index operations are also supported.
One method for creating a persistent data structure is to use a platform provided ephemeral data structure such as an array to store the data in the data structure and copy the entirety of that data structure using copy-on-write semantics for any updates to the data structure. This is an inefficient technique because the entire backing data ...
Given an element of a disjoint union A + B, it is possible to determine whether it came from A or B. If an element lies in both, there will be two effectively distinct copies of the value in A + B, one from A and one from B. In type theory, a tagged union is called a sum type. Sum types are the dual of product types.
A snippet of Python code with keywords highlighted in bold yellow font. The syntax of the Python programming language is the set of rules that defines how a Python program will be written and interpreted (by both the runtime system and by human readers). The Python language has many similarities to Perl, C, and Java. However, there are some ...
bool is_negative (float x) {union {int i; float d;} my_union; my_union. d = x; return my_union. i < 0;} Accessing my_union.i after most recently writing to the other member, my_union.d , is an allowed form of type-punning in C, [ 6 ] provided that the member read is not larger than the one whose value was set (otherwise the read has unspecified ...
Array, a sequence of elements of the same type stored contiguously in memory; Record (also called a structure or struct), a collection of fields Product type (also called a tuple), a record in which the fields are not named; String, a sequence of characters representing text; Union, a datum which may be one of a set of types
The arrays are heterogeneous: a single array can have keys of different types. PHP's associative arrays can be used to represent trees, lists, stacks, queues, and other common data structures not built into PHP. An associative array can be declared using the following syntax: