Why should we typedef a struct so often in C?

Question

I have seen many programs consisting of structures like the one below

typedef struct 
{
    int i;
    char k;
} elem;

elem user;

Why is i

Answer 1

Let's start with the basics and work our way up.

Here is an example of Structure definition:

struct point
  {
    int x, y;
  };

Here the name point is optional.

A Structure can be declared during its definition or after.

Declaring during definition

struct point
  {
    int x, y;
  } first_point, second_point;

Declaring after definition

struct point
  {
    int x, y;
  };
struct point first_point, second_point;

Now, carefully note the last case above; you need to write struct point to declare Structures of that type if you decide to create that type at a later point in your code.

Enter typedef. If you intend to create new Structure ( Structure is a custom data-type) at a later time in your program using the same blueprint, using typedef during its definition might be a good idea since you can save some typing moving forward.

typedef struct point
  {
    int x, y;
  } Points;

Points first_point, second_point;

A word of caution while naming your custom type

Nothing prevents you from using _t suffix at the end of your custom type name but POSIX standard reserves the use of suffix _t to denote standard library type names.