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In the C family of languages and ALGOL 68, the word cast typically refers to an explicit type conversion (as opposed to an implicit conversion), causing some ambiguity about whether this is a re-interpretation of a bit-pattern or a real data representation conversion. More important is the multitude of ways and rules that apply to what data ...
For example, in ANSI C: int add_one ( int x ) { int result ; /* declare integer result */ result = x + 1 ; return result ; } The signature of this function definition, int add_one(int x) , declares that add_one is a function that takes one argument, an integer , and returns an integer.
Implicit conversion is defined for numeric types (as well as booleans), so one may validly multiply a complex number by an integer (for instance) without explicit casting. However, there is no implicit conversion between, for example, numbers and strings ; a string is an invalid argument to a mathematical function expecting a number.
Examples (c is a variable): keyboard ? c screen ! c SEQ introduces a list of expressions that are evaluated sequentially. This is not implicit as it is in most other programming languages. Example: SEQ x := x + 1 y := x * x PAR begins a list of expressions that may be evaluated concurrently. Example: PAR p() q()
The latter types are examples of applications of type functions, for example, from the set {, , , , }, where the superscript indicates the number of type parameters. The complete set of type functions C {\displaystyle C} is arbitrary in HM, [ note 3 ] except that it must contain at least → 2 {\displaystyle \rightarrow ^{2}} , the type of ...
A trivial example of an implicit data structure is an array data structure, which is an implicit data structure for a list, and requires only the constant overhead of the length; unlike a linked list, which has a pointer associated with each data element, which explicitly gives the relationship from one element to the next.
Expressing code in this form makes a number of things explicit which are implicit in direct style. These include: procedure returns, which become apparent as calls to a continuation; intermediate values, which are all given names; order of argument evaluation, which is made explicit; and tail calls , which simply call a procedure with the same ...
For example, consider variables a, b and c of some user-defined type, such as matrices: a + b * c. In a language that supports operator overloading, and with the usual assumption that the '*' operator has higher precedence than the '+' operator, this is a concise way of writing: Add(a, Multiply(b, c))