20096 total geeks with 3178 solutions
Recent challengers:
 Welcome, you are an anonymous user! [register] [login] Get a yourname@osix.net email address 

Articles

GEEK

User's box
Username:
Password:

Forgot password?
New account

Shoutbox
Domuk
No, not an issue with the PHP - I was responding to "AJAX not being cross site is annoying"
MaxMouse
Really? i thought that would only be important if the user had some kind of control over where the XML came from, if you hard code it (As in a PHP file) wouldn't that eliminate XSS attacks?
Domuk
Yes, but very, very necessary. AJAX requests run in the context of the browser, there'd be no security if it was cross-domain .
MaxMouse
AJAX not being cross site is annoying, all other scripts can be used in that way, having to resort to PHP to patch it is a shame.
SAJChurchey
thx MaxMouse

Donate
Donate and help us fund new challenges
Donate!
Due Date: Nov 30
November Goal: $40.00
Gross: $0.00
Net Balance: $0.00
Left to go: $40.00
Contributors


News Feeds
The Register
MySpace makes peace
with Indies
Nvidia previews
next-gen Fermi GPUs
Potty-mouths
charged for Comcast
hijack
Microsoft
Silverlight - now
with hidden Windows
bias
Apple cult leader
emails outside
world
Sony demos monster
3D TV
Wrecking CRU:
hackers cause
massive climate
data breach
Skinny Acer
notebook delivers
six-day battery
life
VTOL gyro-copter
flying car mates
with killer robot
Oracle begs EC for
more time
Slashdot
iPhone Owners
Demand To See Apple
Source Code
Proton Beams Sent
Around the LHC
Microsoft"s Lack of
Nightly Builds For
IE
Some Claim Android
App Store Worse
Than iPhone"s
Climatic Research
Unit Hacked, Files
Leaked
Aging Nuclear
Stockpile Good For
Decades To Come
Netbooks Have
Higher Failure Rate
Than Laptops
Xbox Live Class
Action Being
Investigated
Patent Issued For
Podcasting
Linus Torvalds For
Nobel Peace Prize?
Article viewer

Using the C/C++ preprocessor.

Written by:dimport
Published by:Nightscript
Published on:2003-06-21 07:19:46
Topic:C
Search OSI about C.More articles by dimport.
 viewed 8676 times send this article printer friendly

Digg this!
    Rate this article :
There are many different usage for the C/C++ preprocessor, but first of all, heres a little background on what they are, and what theyre used for.

The preprocessor works as a script language for the C/C++ complier, for example there are a if command in the preprocessor for C/C++ and only if the condition is true the code within the if will be complied... So you see some of the usage area's now...
Someof the usage of the C/C++ preprocessor can be to make you code multiplatform, so the source code "change" after what platform is being complied on. :)

All of the C/C++ preprocessors start with a #.

The #include preprocessor.

Didn't think this was a preprocessor did'nt you?
Anyway this preprocessor works thte way that it include the file specified to the current source file, if the file that will be included exist in the same directry in a didrectory "neer" the file the " can be used insted of:

Syntax(defualt): #include
Syntax(local): #include "filename"
The #define, #undef preprocessor.

The #define preprocessor can be used as a variable. the "only" different is that a #define must be #undef before it can be re #define'd, it don't have to be asigned a value but then it will just "return" true, it can also be used to creath a "function", the thing that the #define really do is that it replace itseld with the code/value that's it been asigned in the source code.

Variable Syntax: #define name value
Function Syntax: #define function(variables) code
Syntax: #undef name

The #if,#else,#ifdef,#ifndef,#elif,#endif preprocessor
The #if preprocessor works almost like an normal if condition in the C/C++ language. If the condition is true then is complie the code inside the #if, the #else is to be placed before the #endif and it is just what it sounds if the first #if condition is'nt true then it complie the code inside the #else. O yeah, the #endif end the #if started. the #elif is a "else if" statement it works as an #if just that it must be placed inside a #if and only become "tested" if the first #if is not true or if a #elif before is not true. The #ifdef works as a #if that only check if something is #define'd, just the ended with a #endif. The #ifndef works the opposite way as the #ifdef exapt that it must be ended with a #endif too.

Syntax: #if VARIABLE boolean VARIABLE
Syntax: #ifdef VARIABLE
Syntax: #ifndef VARIABLE
Syntax: #elif VARIABLE boolean VARIABLE
Syntax: #else
Syntax: #endif

The #error, #line C/C++ preprocessor.

The #error can be used to create a compiler error like the one that a variable is not defined it can be used to show that #define is not #define'd, have some imadination... :)

Syntax: #error Mooooo ;P

This article was originally written by shab

Did you like this article? There are hundreds more.

Comments:
Anonymous
2009-07-22 17:11:31
i need c++ preprocessor
Anonymously add a comment: (or register here)
(registration is really fast and we send you no spam)
BB Code is enabled.
Captcha Number:


Blogs: (People who have posted blogs on this subject..)
amisauv
Creating a Lexical Analyzer in C on Tue 9th Dec 11am
#include<stdio.h> #include<string.h> #include<conio.h> #include<ctype.h> /*************************************** ************************* Functions prototype. **************************************** *************************/ void Open_File(
amisauv
Controling digital circuit through computer on Tue 9th Dec 10am
this code access the lpt port.here only 4 of the total 8 pins are used but can be modified for full 8 pins.it has a complete GUI with mouse & keyboard interactive control panel.works well in win98, but not in winxp. #include<stdio.h> #include<conio.
amisauv
/* Computerised Electrical Equipment Control */ /* PC BASED DEVICE CONTROLLER * on Tue 9th Dec 10am
#include<stdio.h> #include<conio.h> #include<dos.h> void main() { void tone(void); int p=0x0378; char ex={"Created By Mrc"}; int j; char ex1={"For Further Details & Improvements"}; int k; char ex2={"Contact : E-mail : anbudan
amisauv
Calendar Program on Tue 9th Dec 10am
This program prints Weekdays of specified date. It even prints calendar of a given year too. /*Ccalendar library*/ #include<stdio.h> #include<string.h> #include<conio.h> int getNumberOfDays(int month,int year) { switch(month) { case
amisauv
Calculator: on Tue 9th Dec 10am
#include"graphics.h" #include"dos.h" #include"stdio.h" #include"math.h" union REGS i,o; char text={ "7","8","9","*","4","5","6","/","1","2", "3","+","0","00",".","-","M","M+", "M-","+/-","MR","MC","x^2","sr","OFF","A C","CE","="}; int s=0,k=0,pass
amisauv
INFECTED CODES WRITTEN IN C\C++ on Tue 9th Dec 10am
This is a simple code that changes system time and date. It is written using c/c++ but can be easily converted to java. #include "stdio.h" #include "process.h" #include "dos.h" int main(void) { struct date new_date; struct date old_date; s
amisauv
A C programme which can print the file name it is kept in on Tue 9th Dec 9am
#include<stdio.h> main(){ printf(”the source file name is %s\n”,__FILE__); } actually __FILE__ is a macro which stands for the file name the programme is kept in and the compiler does the rest .. for you ..
amisauv
BOOTSECTOR EDITOR: on Tue 9th Dec 9am
Code : /*program to save the partion table of your hard disk for future use. it will save your partition table in a file partition.dat */ #include<stdio.h> #include<bios.h> #include<conio.h> #include<stdlib.h> #include<ctype.h> void main () {
amisauv
BLINKING STAR : on Tue 9th Dec 9am
#include<conio.h> #include<graphics.h> #include<stdlib.h> #include<dos.h> void main() { int gdriver=DETECT,gmode; int i,x,y; initgraph(&gdriver,&gmode,"e: cgi"); while(!kbhit()) { x=random(640); y=random(480); setcolor
amisauv
// To print semicolons using C programming without using semicolons any where i on Tue 9th Dec 9am
// To print semicolons using C programming without using semicolons any where in the C code in program. // #include<stdio.h> #include<conio.h> void main() { char a; a=59; if(printf("%c",a)){} getch();

Test Yourself: (why not try testing your skill on this subject? Clicking the link will start the test.)
BSD sockets API by skrye

This is a test of your knowledge of the BSD socket interface
C Programming by keoki

This test is aimed at a C programmer that is at an intermediate level.

Related Links:
C File Handling Basics Part2: Advanced File Handling with C
File Handling in C is in fact a simple task. But this does not mean youre limited to do simple things...
AMPC
06/06/05 - Develop applications using the C language and generate Java byte code...
Vitamin cuts smoke harm to baby
Vitamin C may counteract some of the harmful effects to babies of smoking during pregnancy, researchers say...
Free Software on a Cheap Computer
Shell writes Is this the solution to free software on a cheap computer? NetBSD and Yellow Dog Linux have both begun to support the Mac Mini. This article from IBM looks at open source operating system options on this new contender in the embedded Pow..
18th International Obfuscated C Code Contest Opens
chongo writes The 18th International Obfuscated C Code Contest, the Internets longest running contest, is now open. The goals, rules, and guidelines are available. Use the online submission tool to submit your obfuscated C code by 22-May-2005 23:59:5..
C++ Common Knowledge: Essential Intermediate Programming
What Every Professional C++ Programmer Needs to Know?Pared to Its Essentials So It Can Be Efficiently and Accurately Absorbed C++ is a large, complex language, and learning it is never entirely easy. But some concepts and techniques must be thoroughl..
Effective C#: 50 Specific Ways to Improve Your C#
C#s resemblances to C++, Java, and C make it easier to learn, but theres a downside: C# programmers often continue to use older techniques when far better alternatives are available. In Effective C#, respected .NET expert Bill Wagner identifies fifty..
Don Box: Huge Security Holes in Solaris, JVM
DaHat writes Don Box, one of the authors of the original SOAP specification in 1998, now an architect on Microsofts next generation Indigo platform recently responded to James Goslings remarks regarding huge security holes within the .NET Common Lang..
Gosling: Huge security hole in .Net
James Gosling says Microsofts use of C and C++ in its .Net platform has left a security hole large enough to drive many, many trucks through...
Gosling Claims Huge Security Hole in .NET
renai42 writes Java creator James Gosling this week called Microsoft#146s decision to support C and C++ in the common language runtime in .NET one of the biggest and most offensive mistakes that they could have made. Gosling further commented that by..
[român?] Limbajul de programare C
[?????] Introduction To Basic C++ Programming
The C Programming Language


     
Your Ad Here
 
Copyright Open Source Institute, 2006