PROGRAMMING POINTERS, LESSON 6

Syntax/correctness issues

6-1       The data type of the return value of a function must match the data type in the function prototype.

6-2       Forgetting to return a value from a function, which is supposed to return one, will lead to unexpected errors in a program.

6-3       In a function prototype, the parameter must include the data types of values to be passed; identifiers are optional.  Also, each function prototype must end with a semicolon.

int doSomething (int x,y);     //  syntax error, the y needs a data type

int doItRight (int x,  int y);    //  this is acceptable

int P (int, int);            //  this is also acceptable

6-4       When writing the function definition, do not place a semicolon after the parameter list.

int doItRight (int x,  int y);    //  <--- no semicolon on this line, this will not compile

            {

                // some code

            }

6-5       Do not define a function inside another function.  C++ does not allow for nested definitions.

6-6       Function prototypes are required in C++.

Formatting suggestions

6-7       Separate the implementation of functions with blank lines to enhance their readability.

Software engineering

6-8       Function main should consist of calls to other functions which accomplish the work of the program.

6-9       Each function should solve a single, well-defined task.  The name of the function should help describe the task of the function.

6-10     Functions should be no longer than one page.  If possible, keep functions short.  This will make it easier to read and debug your code.

6-11     A function which contains a large number of parameters may be trying to do too much.  Consider breaking the function down into smaller functions.

6-12     Global variables should be avoided as they allow side-effects to occur.  A side-effect is an unintended change to a global variable from inside a function.  Variables which exist during the entire execution of the program should be declared in function main and then passed to other functions through parameters.