What is meant by the guest function, Computer Engineering

Assignment Help:

When  transferring  one  function  to  another,  what  is  meant  by  the  guest  function?

A pointer to a function can be passed to another function as an argument. This allows one function to be transferred to another, as though the first function were a variable. This  is  very  useful  in  scientific  programming.  Imagine  that  we  have  a  routine  which numerically integrates a general one-dimensional function. Ideally, we would like to use this routine to integrate more than one specific function. We can achieve this by passing (to the routine) the name of the function to be integrated as an argument.

The function whose name is passed as an argument is called guest function. Likewise, the function to which this name is passed is called the host function. A pointer to a guest function is identified in the host function definition by an entry of the form data-type  (*function-name)(type 1,  type 2, ...) in the host function's argument declaration. Here, data-type is the data type of the guest function, function-name is the local name of the guest function in the host function definition, and type 1, type 2, ... are the data types of the guest function's arguments. The pointer to the guest function also requires an entry of the form data-type  (*)(type 1, type 2,  ...) in the argument declaration of the host function's prototype. The guest function can be accessed within the host function definition by means of the indirection operator. To achieve this, the indirection operator must precede the guest function name, and both the indirection operator and the guest function name must be enclosed in parenthesis: i.e.,

 

(*function-name)(arg 1, arg 2,  ...)

Here, arg 1, arg 2,... are the arguments passed to the guest function. Finally, the name of a guest function is passed to the host function, during a call to the latter function, via an entry like "function-name" in the host function's argument list.

The program listed below is an example which illustrates the passing of function names as arguments to another function:

/* passfunction.c */

/*

Program to illustrate the passing of function names as arguments to other functions via pointers

*/

#include

/* Function prototype for host fun. */

void cube(double (*)(double), double, double *);

double fun1(double);   // Function prototype for first guest function

double fun2(double);

int main()

 

{

// Function prototype for second guest function

double x, res1, res2;

/* Input value of x */ printf("\nx = "); scanf("%lf", &x);

/* Evaluate cube of value of first guest function at x */

cube(fun1, x, &res1);

/* Evaluate cube of value of second guest function at x */

cube(fun2, x, &res2);

/* Output results */

printf("\nx = %8.4f  res1 = %8.4f   res2 = %8.4f\n", x, res1, res2);

return 0;

}

void cube(double (*fun)(double), double x, double *result)

{

/*

 


Related Discussions:- What is meant by the guest function

Determine frequency of a dtmf phone, In a DTMF phone a dialling of 8 genera...

In a DTMF phone a dialling of 8 generates (A) 1336 Hz- 770 Hz                      (B)  1209 Hz - 1477 Hz (C)  1209 Hz- 941 Hz                     (D)  1336 Hz-852 Hz

Instruction issue degree, Instruction Issue degree : The major concept in s...

Instruction Issue degree : The major concept in superscalar processing is how many instructions we can issue per cycle. If we issue k number of instructions per cycle in a supersca

What is time multiplexed space switching, What is time multiplexed space sw...

What is time multiplexed space switching? Explain w ith a neat diagram. Time division switches, an inlet or an outlet corresponded to a particular subscriber line with one s

SIDE EFFECT , EXPLAIN SIDE EFFECT OF SCAN CONVERSION WITH DIGRAM

EXPLAIN SIDE EFFECT OF SCAN CONVERSION WITH DIGRAM

What are the requirements of the user, This step of systems examination is ...

This step of systems examination is one of the most difficult. In this stage systems specifications are identified by asking what, who, when, where and how. A few questions address

Layered architecture of electronic data interchange, Illustrated about the ...

Illustrated about the layered architecture of Electronic Data Interchange? Layered Architecture of EDI: Electronic Data Interchange is most commonly applied into th

Explain the page stealer and the fault handler, How the Kernel handles both...

How the Kernel handles both the page stealer and the fault handler? The page stealer and the fault handler thrash because of the shortage of the memory. If the sum of the worki

Explain about integration levels, Q. Explain about Integration Levels? ...

Q. Explain about Integration Levels? Initially only few gates were integrated consistently on a chip. This initial integration was termed as small-scale integration (SSI). With

Search-based tools, The search-based tools initially identify the problem a...

The search-based tools initially identify the problem and after that appropriately give advice on how to correct it. AT Expert from Cray Research is one of the tools being used

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