High School Mathematics Extensions/Mathematical Programming/Sample C Program

Programming is an iterative process. This sample will walk you through creating a C program that allows you to evaluate the function X^2 using intervals that you define. This program will serve as a basis for exploring issues in the Mathematical Programming section of the High School Mathematics Extensions Wikibook.

The following pages will be divided into three parts:

An explanation of the code provided on the page.
Code that you should be able to paste into your editor and compile.
A link to the next iteration in the development of the sample program.

Explanation

What this program does.

Main()

Define a character variable called command.
Call the void function init to get ready to make sure the global variables are correctly set up.
Call the void function input_message to prompt the user.
Loop while the global variable done is set to false.

Call the function input to initialize the variable command. Call the function execute_command to process the command.

init()

Sets done to FALSE.

input_message()

Prints the message "Press a key to continue: \n" to the console.

input()

Reads a character from the console.

execute_command(command)

Sets the global variable done to true.

This sample program is divided into five sections

1. Header Files

Header files can be user defined or linked to a library. One purpose of user defined include files is to provide modularity and re-use. That is currently not an objective for this program.

2. Function Prototypes

Function prototypes tell the compiler to create a definition for a function that hasn't been defined yet. Stylistically I find it easier to add prototypes for my functions at the head of the file. This allows me to add functions on the fly as I develop. If I have a project with multiple project files I move the function prototype into a header file that I include in the files that use the functions I defined.

3. Type Definitions

Place where to put typedef decelerations.

4. File Variables

File variables are a style choice. Your style will probably be different than mine. If you decide to use file variables in your programs I recommend declaring them in one place in your source file.

5. function definitions

Implementation of the functions you declared as prototypes.

Code to copy

The following code is valid:

 //includes
 #include <stdio.h>
 #include <conio.h>

 //function prototypes
 void init();
 void input_message();
 char input();
 void execute_command(char);

 //type definitions 

 //global variables
 char done;

 //function definitions
 void init()
 {
     done=0; 
 }
 void input_message()
 {
     cprintf("Press a key to continue: \n");
 }
 char input()
 {
     char read;
     read=getche();
     return(read);
 }
 void execute_command(char command)
 {
     done=1; 
 }
 void main()
 {
    char command;
    init();
    input_message();
    while(!done)
       {
        command=input();
        execute_command(command);
       }
 }

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