At first glance, adding a typedef to a struct in C seems to complicate the definition. However, it simplifies the declaration of the structure. This is not always recommend, as it can add a layer of obfuscation.

Structures

Here is how a normal structure is defined in C.

#include <stdio.h>
#include <string.h>

struct Cat {      // defining Cat structure
  char name[20];  // members of Cat structure
  int age;
  int weight;
};

int main() {
  struct Cat myCat;  // declaring Cat structure, myCat
  
  strcpy( myCat.name, "Cleopatra");  // setting member values
  myCat.age = 4;
  myCat.weight = 10;

  return 0;

}

In the example above, notice declaring myCat on Line 11 is “struct Cats myCat”. We are about to see how typedef will shorten this.

Typedef

#include <stdio.h>
#include <string.h>

typedef struct {  // defining Cat structure
  char name[20];  // members of Cat structure
  int age;
  int weight;
} Cat;

int main() {
  Cat myCat; // declaring Cat structure, myCat

  strcpy( myCat.name, "Cleopatra"); // setting member values
  myCat.age = 4;
  myCat.weight = 10;

return 0;
}

Notice how Line 11 has shortened to “Cat myCat”.

When declaring many structs throughout a large project, this can save some typing and sometimes increase readability.

Criticism

Typedefs on structure isn’t popular with everyone. Most prominently, the Linux kernel does not use typedefs for structures. A quote from the Linux Kernel Coding Style:

“It’s a **mistake** to use typedef for structures and pointers. When you see a

you can actually tell what “a“ is.”

Nonetheless, you are sure to encounter typedef structures. Try not to add any more to the world.