More Function Stuff

The end of chapter 7

• Function Documentation
  • Block comment before the function.
  • Describe the function
  • Describe the parameters
  • List pre/post conditions
  • They like to label their parameters too

    void foobar(/* in */ int aparam, 
                /* out */ float & bparam,
    	    /* inout */ char & cparam);
          

• A rule of thumb: use lots of functions

Chapter 8

• Goals
  • Discuss the scope of a variable
  • Define local and global variables.
  • Determine the lifetime of a variable
  • Define and explain side effect
  • Correctly use value returning functions
• Some Definitions
  • Scope: The region of a program where it is legal to reference a variable
  • Local Scope: the block in which the identifier is declared
  • Global Scope: Identifiers declared outside of a block
  • Function names have global scope.
  • Class Scope: Chapter 12
  • Scope Rules
    1. Functions have global scope, and cannot be nested
    2. Parameters are identical to local variables
    3. Global variables and constants are from definition to the end of the program
    4. Local Varaibles are within their block
    5. name prescidnce applies to local variables.

       {
          int foo;
          ...
          { 
             int  foo
       
             foo = 4
          }
       }
       	   

  • Don't use global variables
  • You may use global constants (it is a good thing)
  • namespace : creating a named scope.
  • Lifetime: the period of time durring the execution of the program when a variable has a value.
  • Dynamic: variables allocated when their lifetime begins
  • Static: Variables who's allocation is throught the entire program
  • static int foo=4;
  • Side effect - from global variables only
    • Any effect of one function on another that is not part of the explicitly defined interface between them.
• Value returning functions
  • int foo() { ....
  • return (4);
• Testing and Debugging
  • Stubs and Drivers.