Organisation of Data in each File

Any file must have its data organised in a certain order. This will typically be:

1. A preamble consisting of #defined constants, #included header files and typedefs of important datatypes.
2. Declaration of global and external variables. Global variables may also be initialised here.
3. One or more functions.

Within each of these sections, the order of items is important, since any object must be defined before it can be used. In particular, functions which return values must be defined in the file before they are called. This definition might be one of the following:

• Where the function is defined and called in the same file, a full declaration of the function can be placed ahead of any call to the function.
• If the function is called from a file where it is not defined, a dummy declaration should be made.

  float find_max(a, b, c)
  float a, b, c;
  {  /* etc ... ... */

  float find_max();

It is most important to remember that all C objects should be declared before they are used.