C Programming - Memory Allocation - Discussion

Is the following statement a declaration or definition?

extern int i;

A. Declaration B. Definition
C. Function D. Error

Answer & Explanation

Answer: Option A.

Explanation:

Declaring is the way a programmer tells the compiler to expect a particular type, be it a variable, class/struct/union type, a function type (prototype) or a particular object instance. (ie. extern int i).

Declaration never reserves any space for the variable or instance in the program's memory; it simply a "hint" to the compiler that a use of the variable or instance is expected in the program. This hinting is technically called "forward reference".

malloc() and calloc() are used to allocate space in memory but one difference is there allocating methods.

malloc() : malloc(int) only passing one arguments int allocates 2 bytes.

calloc() : calloc(int,5) passing two arguments int allocates 2 bytes, also 5 times 2 bytes will allocates.

Both allocate storage memory but the difference is malloc process single argument so just specify storage space while calloc process double argument so specify no. Of variable and space needed for that variable.

Memory allocated by malloc or calloc : deallocated by free().
Memory allocated by new(in c++) : deallocated by delete().

We doesn't functions like dealloc() in "C" and the remaining options are to allocate memory so may the answer is free().

free() is one of the predefined function its free memory ...
only one function is there in c language to free memory....

There are only 3 memory allocation functions in C calloc(),malloc() and free(). free is to free that allocated space

@N. Gayathridevi.

In c++ editor goto help and look for alloc.h.

In that header file examples are given.

In C editor goto alloc.h you will find answer to this question and other memory management func:'s.

How is different between malloc() and calloc() what is function of both? How it work?