GATE CSE 1994 | Question: 18a

Question

State whether the following statements are True or False with reasons for your answer

A subroutine cannot always be used to replace a macro in an assembly language program.

Comments

can someone explain in detail ????

Answer 1

$\textsf{TRUE}.$

A macro is evaluated at compile time whereas a function call happens at runtime. So, we can write a macro to rename any symbol which is not possible to be replaced by a simple subroutine call. For example consider the following $C$ code.

#define type int
type foo (type arg1)
{
    ...
}
#undef type

In the above code a macro is used to define a type which is used as the return and argument types for the function $\textsf{foo}.$ This is not possible to be implemented as a simple subroutine call (but can be done using $\textsf{typedef}$ is the language supports it).

Comments

Nice eg.

Answer 2

This is true. We can not replace macro entirely using a subroutine. Ex: Macro constant used for renaming.

Comments

@Ayush

by tp what do u mean?

I cannot understand

---

#include<stdio.h>

#define ch char

int main()

{

   ch a,b;

   return 0;

}

 

There is No function which can do this work instead of macro

ASSEMBLY ==> SUB-Routine

High-Level ===> Function

---

so means we must require coroutine here