we have to use realloc only after malloc or calloc ? or we can use initially w

we have to use realloc only after malloc or calloc ? or we
can use initially with out depending on whether we are
using malloc or calloc in our program ?

Question Posted / prakash

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we have to use realloc only after malloc or calloc ? or we can use initially with out depending on..

Answer / vadivel t

Hi Vignesh,

Ur explanation about realloc() is correct. But the answer
is wrong. Because, it is possible to use realloc() before
using malloc() or calloc() function be used.

Lets, try the below code.

int *ptr;
ptr = (int *)realloc(NULL, 5);
printf("%d \n", ptr);

In this code, realloc will allocate five bytes of memory
and will return a valid pointer. It can be used in ur
program.

Conclusion:

It simple means that, if u pass a NULL pointer to a realloc
() function, it will exactly behave as like malloc().

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we have to use realloc only after malloc or calloc ? or we can use initially with out depending on..

Answer / vignesh1988i

ya we must use realloc (RE-ALLOCATION) only after malloc (MEMORY ALLOCATION) ....
actually realloc is a fuction which will be mainly implemented after knowing the accurate amount of memory that is going to be used... if our memory is allocated using malloc is less compared to the total values that is going to be stored we will RE-ALLOCATE the memory to our wish to store all the values...

but in other case if the data has been stored in the allocated block by malloc , but still more is remaining we can again RE-ALLOCATE usin realloc funcion.......

thank u

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