malloc: size of allocated area?

[luckycusp]

How to find the size of area allocated by malloc?? is it even possible.


for example:-

void *ptr;
ptr = malloc(10);


Here malloc should allocate 10bytes...

Can i check it in my program using 'ptr' variable, how many bytes are allocated??
Maybe using sizeof().. but how?

[bnbertha]

There is no standard way of doing this. You may be lucky and your implementation/platform has an extension to do this but otherwise the only way is to track it yourself from when the malloc() was done.

See this C language FAQ http://c-faq.com/malloc/querysize.html