Recursion versus iteration, PL-SQL Programming

Assignment Help:

Recursion versus Iteration

Dissimilar the iteration, recursion is not crucial to PL/SQL programming. Any problem which can be solved using recursion can be solving using the iteration. Also, the iterative version of the subprogram is typically easier to design than the recursive version. Though, the recursive version is typically simpler, smaller, and hence easier to debug. Compare the functions below that calculate the nth Fibonacci number:

-- recursive version

FUNCTION fib (n POSITIVE) RETURN INTEGER IS

BEGIN

IF (n = 1) OR (n = 2) THEN

RETURN 1;

ELSE

RETURN fib(n - 1) + fib(n - 2);

END IF;

END fib;

-- iterative version

FUNCTION fib (n POSITIVE) RETURN INTEGER IS

pos1 INTEGER := 1;

pos2 INTEGER := 0;

cum INTEGER;

BEGIN

IF (n = 1) OR (n = 2) THEN

RETURN 1;

ELSE

cum := pos1 + pos2;

FOR i IN 3..n LOOP

pos2 := pos1;

pos1 := cum;

cum := pos1 + pos2;

END LOOP;

RETURN cum;

END IF;

END fib;

The recursive version of the Fibonacci is more graceful than the iterative version. Though, the iterative version is more accurate; it runs faster and uses less storage. That is as each recursive call needs an additional time and memory. As the number of recursive calls gets bigger, so does the difference in effectiveness. Still, if you expect the number of recursive calls to be little, you may choose the recursive version for its readability.


Related Discussions:- Recursion versus iteration

Mutual recursion, Mutual Recursion The Subprograms are mutually recursi...

Mutual Recursion The Subprograms are mutually recursive if they directly or indirectly call each other. In the illustration below, the Boolean functions odd & even, that dete

Sqls counterpart of the key words, SQLs counterpart of the key words: ...

SQLs counterpart of the key words: The text from the opening parenthesis to the end of the fourth line specifies the declared type of the table, meaning that every table ever

Using trim - collection method, Using TRIM This process has two forms....

Using TRIM This process has two forms. The TRIM removes an element from the end of the collection. The TRIM(n) removes the n elements from the end of the collection. For e.g.

Components of an object type - parameter self, Parameter SELF in pl/sql ...

Parameter SELF in pl/sql The MEMBER methods recognize a built-in parameter named SELF that is an instance of the object type. Whether declared explicitly or implicitly, it is

In packages - subprograms, In Packages The Forward declarations also g...

In Packages The Forward declarations also group logically related subprograms in the package. The subprogram specifications go in the package specification, & the subprogram b

Declaring exceptions - user-defined exceptions, Declaring Exceptions T...

Declaring Exceptions The Exceptions can be declared only in the declarative part of the PL/SQL subprogram, block, or package. By introducing its name, you can declare an excep

Object types - syntax, Object Types An object type is a user-defined co...

Object Types An object type is a user-defined complex datatype which encapsulates the data structure along with the functions and procedures required to manipulate the data. Th

Defining ref cursor types, Defining REF CURSOR Types To make cursor va...

Defining REF CURSOR Types To make cursor variables, you take 2 steps. At first, you define a REF CURSOR type, and then declare the cursor variables of that type. You can defin

Use native dynamic sql - improve performance of application, Use Native Dyn...

Use Native Dynamic SQL A few programs (a normal-purpose report writer for illustration) should build and process a variety of SQL statements at run time. Therefore, their full

Cursor attributes in dynamic sql - pl sql, Using Cursor Attributes: Ev...

Using Cursor Attributes: Every cursor has 4 attributes: %NOTFOUND, %FOUND, %ISOPEN, and %ROWCOUNT. If appended to the cursor name, they return the helpful information about

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd