Changes

Below is a program with duplicated code. It performs the same 3 similar operations on 3 different axes to Enable, Move, and Wait an Axis. Notice the same operations are performed each time with only two differences: the Axis and the distance moved. So by using a function with two parameters we can replace the 3 instructions with a single function call. The first parameter is which Axis which is an integer value. The second parameter is the distance to move which is a double precision value.

main()

{

Now declaring a function named EnableMoveWait with 2 parameters (and void return value) we can simplify the C Program, lessen the number of total instructions in the program, and most importantly guarantee that the exact same operations are performed for each axis.

// define function to Enable, Move, and wait with two parameters

It is often desirable to place the functions toward the end of file with the main starting point of the program toward the beginning. This tends to make the program more readable and logical. This is not necessary but more a personal preference. Because the C Compiler only reads the program one time from beginning to end it is good to place at the beginning a description of any Functions that exist in the program. The allows the compiler to know the names of any functions and what parameter and return value types they have before they are used in the program. It is critical that the parameters passed in the call to the function are the exact correct number and type that are defined to be used by the function itself. So to inform the compiler of what function to expect a "function prototype" is specified. This is exactly the same as the function declaration itself except with no body of instructions. It consists of only one line followed by a semicolon to indicate it is only a prototype and not the entire function. See the Program below that has the function moved below the main function and with a function prototype at the beginning:

// define function prototype of function to expect later