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?

void main(){

int *ptr;

printf("%d",sizeof ptr);

}

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?

void main(){

char (*fun)();

printf("%d",sizeof fun);

}

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?

void main(){

int near *p,*q;

printf("%d , %d",sizeof(p),sizeof(q));

}

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?

void main(){

char huge **p;

printf("%d , %d",sizeof(p),sizeof(*p));

}

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?

void 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

}

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