Memory model in c programming

Memory model:

In c there are six type of memory model.
If you want to see all memory model in Turbo C++ IDE then open Turbo C++ IDE and the go:
Options menu -> Compiler -> Code generation

These memory models are:

(a) TINY
(b) SMALL
(c) MEDIUM
(d) COMPACT
(e) LARGE
(f) HUGE

If you want to change the memory model then go to:

Options menu -> Compiler -> Code generation

And select any memory model and click OK button.




Properties of memory mode in C:

(1) Memory model decides the default type of pointer in C.



Note:

Code: A pointer to function is called code.
Data: A pointer to variable is called data.

Examples:

(1)What will be output of following c program?


#include<stdio.h>
int main(){

int *ptr;
printf("%d",sizeof ptr);


return 0;
}

Output: Depends upon memory model.
Explanation: If memory model is TINY, SMALL or MEDIUM then default pointer will near and output will be 2 other wise output will be 4.

(2)What will be output of following c program?


#include<stdio.h>
int main(){

char (*fun)();
printf("%d",sizeof fun);


return 0;
}

Output: Depends upon memory model.
Explanation: fun is pointer to function. If memory model is TINY, SMALL or COMPACT then default pointer will near and output will be 2 other wise output will be 4.

(3)What will be output of following c program?


#include<stdio.h>
int main(){
int near *p,*q;
printf("%d , %d",sizeof(p),sizeof(q));


return 0;
}

Output: 2, Depend upon memory model.
Explanation: p is near pointer while type of pointer q will depend what is default type of pointer.

(4)What will be output of following c program?


#include<stdio.h>
int main(){
char huge **p;
printf("%d , %d",sizeof(p),sizeof(*p));


return 0;
}

Output: 4, Depend upon memory model.
Explanation: p is huge pointer while type of pointer *p will depend what is default type of pointer.

(5)Write a c program to find the memory model of you computer?


#include<stdio.h>
int main(){
   #if defined __TINY__
   printf("Memory model is: TINY");
   #elif defined __SMALL__
   printf("Memory model is:SMALL ");
   #elif defined __MEDIUM__
   printf("Memory model is:MEDIUM ");
   #elif defined __COMPACT__
   printf("Memory model is:COMPACT ");
   #elif defined __LARGE__
   printf("Memory model is:LARGE ");
   #elif defined __HUGE__
   printf("Memory model is:HUGE ");
   #endif


   return 0;

}

(2) Memory models decide the default size of segment.

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