Thread: Help me.. (Dynamic memory allocation )

i am beginner in programming. I want to understand dynemic memory allocation function. i search it google but i dont satisified with it... Can anybody plz explain me dynamic memory allocation function.. malloc(),realloc(),calloc() and freee()..


In school mam do this example ..

Code:

#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#define NULL 0


void main()
{
    int *t,*p,size;
    clrscr();


    printf("Enter size");
    scanf("%d",&size);


    t=(int *)malloc(size * sizeof(int));


    if(t==NULL)
    {
        printf("No space available");


    }


    for(p=t;p<=t+size;p++)
    {
        scanf("%d",p);
    }


    printf("Display table value");


    for(p=t+size-1;p>=t;p--)
    {
        printf("%d values at %u address",*p,p);
    }
getch();
}

Plzz explain me this example ..

Thank you

google 'dynamic memory allocation in c'

thankx

Output is ok. i want to print all 5 number which i entered with address.. i dont understand what our teacher want from this program ..
i dont understand why malloc() is used.. we can print this by simple using for loop.

here output screenshot.

in many website which i searched in google tells malloc include in <stdlib.h> . but our teacher write <alloc.h>
i think i have c++ complier not sure .. how to check ?
my teacher alwys write void main().. grom very first program of printing "hello world"

i dont like my teacher because they don't explain very well. & don't like my univercity also
if you have any good tutorial site please tell me

thankx again in advance

@christop
..
Then what i used for getch(), #include <alloc.h>, #include <conio.h>, and void main ???

i learn form first program to use getch(), void main() and <conio.h>

HERE IS FIRST PROGRAM THAT I LEARNT.

Originally Posted by Devil211272

Output is ok. i want to print all 5 number which i entered with address.. i dont understand what our teacher want from this program ..
i dont understand why malloc() is used.. we can print this by simple using for loop.

Yes you can perform the operation using simple loops. But, the point here is to learn how to use the dynamic memory allocation that is why your teacher has instructed you to use malloc

here output screenshot.

in many website which i searched in google tells malloc include in <stdlib.h> . but our teacher write <alloc.h>
i think i have c++ complier not sure .. how to check ?
my teacher alwys write void main().. grom very first program of printing "hello world"

From the screenshot i can see you are using TurboC which is a very old compiler and this explains why your teacher has instructed you to use <conio.h>, <alloc.h>, clrscr(), getch() all these are specific to TurboC. And i learned C programming in the same environment 10 years back and still it is used in many schools/university without any knowledge about C standards. As @christop pointed out whatever code you are writting in TurboC is going to work in only DOS and its not portable.

Thankx

Can you give me the link of new complier / software for c language for window 7.

There are many compiler available. I am aware of GCC as that is default in linux environment but setting it up in Windows requires more work (It is not suitable for the beginners). Whereas someone else might give you a link on other compilers.

I guess you are from INDIA(As a matter of fact I am) I certainly know most of the teachers (Of-course there are always exceptions) who thought C in schools/university have exposure to TurboC alone and they don't know any other compiler.

Yes me from India. I am not living in big and popular city.. me from jamnagar,Gujarat(india). i study in saurstra university.

There is nothing wrong in learning C programming via TurboC (Provided you know the limitations it imposes). You can start learning in that environment itself and later on move to some modern compilers. One handy tip I remembered is TurboC had a very nice help section which explains all the details along with example codes. Not sure whether this is available in your case but you can give it a try and see for yourself.

For example, place your cursor over the word malloc in your code and press Ctrl+F1 it will open a interactive help section which has details about the call.

Thankx for the tip. Its work well. example is also given there