| |||||||||||
| |||||||||||
Preprocessor directive demonstration
Standard Libraries and other headers example from a Well House Consultants training course
More on Standard Libraries and other headers [link]
Source code: ten.c Module: C211
#include <stdio.h>
/* Demonstration that shows a number of preprocessor directives; the preprocessor is run prior to the main compile stage and alters the source code prior to its conversion to a binary / machine level format */ /* Define some preprocessor constants */ #define START 10 #define END 230 /* Define another preprocessor constant but ONLY if it has not been defined before hand - such as on the command line */ #ifndef STEP #define STEP 10 #endif main () { int current; float degc; /* The preprocessor constants are used in the following statement - by substituting a constant values prior to coversion to a binary format, the resultant executable progam can have the efficienciy of being compiled with unchanging (constant) values, and yet has a degree of flexibility in that it may be recompiled and rebuilt at a later date with different values */ for (current = START; current <= END; current += STEP) { degc = ((float)current - 32.0) / 9.0 * 5.0; printf ("From %3d deg F to %6.2f deg C\n", current, degc); } } /* Compile and run samples, showing command line definition of a preprocesor constant munchkin:capr grahamellis$ gcc -o ten ten.c munchkin:capr grahamellis$ ./ten From 10 deg F to -12.22 deg C From 20 deg F to -6.67 deg C From 30 deg F to -1.11 deg C From 40 deg F to 4.44 deg C From 50 deg F to 10.00 deg C From 60 deg F to 15.56 deg C From 70 deg F to 21.11 deg C From 80 deg F to 26.67 deg C From 90 deg F to 32.22 deg C From 100 deg F to 37.78 deg C From 110 deg F to 43.33 deg C From 120 deg F to 48.89 deg C From 130 deg F to 54.44 deg C From 140 deg F to 60.00 deg C From 150 deg F to 65.56 deg C From 160 deg F to 71.11 deg C From 170 deg F to 76.67 deg C From 180 deg F to 82.22 deg C From 190 deg F to 87.78 deg C From 200 deg F to 93.33 deg C From 210 deg F to 98.89 deg C From 220 deg F to 104.44 deg C From 230 deg F to 110.00 deg C munchkin:capr grahamellis$ gcc -o ten -DSTEP=17 ten.c munchkin:capr grahamellis$ ./ten From 10 deg F to -12.22 deg C From 27 deg F to -2.78 deg C From 44 deg F to 6.67 deg C From 61 deg F to 16.11 deg C From 78 deg F to 25.56 deg C From 95 deg F to 35.00 deg C From 112 deg F to 44.44 deg C From 129 deg F to 53.89 deg C From 146 deg F to 63.33 deg C From 163 deg F to 72.78 deg C From 180 deg F to 82.22 deg C From 197 deg F to 91.67 deg C From 214 deg F to 101.11 deg C munchkin:capr grahamellis$ */ Learn about this subject
This module and example are covered on the following public courses:
* Learning to Program in C * Learning to program in C and C++ * Programming in C * C and C++ Programming * Learning to program in C and C++ * C and C++ Programming Also available on on site courses for larger groups Books covering this topic
Yes. We have over 700 books in our library. Books
covering C and C++ are listed here and when you've selected a
relevant book we'll link you on to Amazon to order.
Other Examples
This example comes from our "Standard Libraries and other headers" training module. You'll find a description of the topic and some
other closely related examples on the "Standard Libraries and other headers" module index page.
Full description of the source code
You can learn more about this example on the training courses listed on this page,
on which you'll be given a full set of training notes.
Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License. Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre. • The Horse's mouth provides a daily tip or thought. • Further resources are available via the resources centre. • All of these resources can be searched through through our search engine • And there's a global index here. Web site author
Purpose of this website
This is a sample program, class demonstration or answer from a
training course. It's main purpose
is to provide an after-course service to customers who have attended our
public private or
on site courses, but the examples are made
generally available under conditions described below.
Conditions of use
Past attendees on our training courses are welcome to use individual
examples in the course of their programming, but must check
the examples they use to ensure that they are suitable for their
job. Remember that some of our examples show you how not to do
things - check in your notes. Well House Consultants take no responsibility
for the suitability of these example programs to customer's needs.
This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details. Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request. |
| ||||||||||
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho PAGE: http://www.wellho.net/resources/ex.php • PAGE BUILT: Sun Oct 11 14:50:09 2020 • BUILD SYSTEM: JelliaJamb |