Help (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 ..

#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 malloc line..

Thank you ..

Plz give me good website for c tutorial

I doubt you'll find someone whose going to give you a detailed explanation about malloc and company. Could you state exactly what your having problems with? Please be specific or Google your general inquires.

After discovering that malloc failed your program must avoid dereferencing the NULL pointer.