Chapter 4: Functions and Program Structure

Chapter 4: Functions and Program Structure

1. Functions

   • Used to separate parts of the code.
   • Declaration Form
   • Can return any type like int, double, string, etc. or nothing (void).

2. External Variables

   • They are used whenever a variable needs to be accessed by many functions.

3. Headers

   • They're used to declare and define for the files.

4. Static Variables

   • They are for the private use of the functions in their respective source files, and are not meant to be accessed by anything else.

5. Register

   • A register declaration advises the compiler that the variable in question will be heavily used.

6. Block Structure

   • Declarations of variables (including initializations) may follow the left brace that introduces any compound statement.
     • Variables declared in this way hide any identically named variables in outer blocks, and remain in existence until the matching right brace.

7. Initialization

   • In absence of explicit initialization, external and static variables are set to 0. Automatic and register are undefined.

8. Recursion

   • Whenever a function calls itself.

9. The C Preprocessor

   • File Inclusion
   • Macro Substitution
   • Conditional Inclusion

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