Appendix: Some minor points about structures and typedef.

Definition and declaration can be combined.

It's possible, although extremely rare, to combine the definition and declaration together. Here we define a structure type and declare an actual structure, mystruct:

int main() {
  struct somestruct {
    int j;
    float x;
  } mystruct;

  // More stuff here..

Structures can be initialised at declaration

So to continue the previous example we may declare another structure and initialise it:

  struct somestruct yourstruct = { 3, 4.5 };

Any declaration can be made into a typedef

Sharp-eyed readers may have noticed that our example typical structure typedef in the main notes:

#define MAXLEN 64
typedef struct nuclide {
  char name[MAXLEN];
  double halflife;
} Nuclide;

has exactly the same form as the combined struction definition above, with the word "typedef" before it. This is a general rule: we may take any valid variable declaration and put the word "typedef" in front of it. When we do this we are not declaring a new variable but a new alias.

Examples