Help me to understand strange 'typedef ... ' in some source... Post: 302983612

Sponsored Content

Top Forums Programming Help me to understand strange 'typedef ... ' in some source... Post 302983612 by jim mcnamara on Thursday 13th of October 2016 09:51:09 PM

10-13-2016

Registered User

That is a typedef of a function. In this case the need was for portability -windows compiler versus maybe a linux C compiler.
No dataype declaration for the function. So, by default, the function will compile probably with a warning as a function that returns an integer.

So you do not worry about the platform, you will notice void * arguments. This lets you call COMPARE_ADDR with any datatypes as long as those datatypes are by reference (address of the object). It does not have a datatype for the function return. This kind of function typedef is usually done for situations where you want to call something to get a standard result, but windows and linux (example platform) do not have the same name for the function, but it may return { <0, 0, >0} for less than, equal to, or greater than.

Pretend example

Code:

#ifdef WIN32 
   COMPARE_ADDR=isequal;
#else
   COMPARE_ADDR=addr_foo;
#endif
/* see if the memory location of two variables is the same */
if  ( ! COMPARE_ADDR( &variable3, &variable1) {  /* if equal barf */
    errno=EINVAL;  /* invalid value error code */
    perror("Cannot continue, variables are identical and must not be identical\n");
    exit(1);   /* end program here */
}

Last edited by jim mcnamara; 10-13-2016 at 11:00 PM..

jim mcnamara

View Public Profile for jim mcnamara

Find all posts by jim mcnamara

9 More Discussions You Might Find Interesting

1. Solaris

Conflicting 'typedef' error - Which gcc switch to use?

I am using gcc3.3.5 on solaris2.7. Its a 64 bit compilation I am compiling a file 'plugin.cpp'. It includes mach.h and the complation gives the following error. ----------------------------------------------------------------- mach.h error: conflicting types for `typedef vx_u32_t...

2. Programming

How to typedef

I want to declare char ch as ch_9 with the help of the typedef statement. Thanks

3. Shell Programming and Scripting

bash shell: 'exec', 'eval', 'source' - looking for help to understand

Hi, experts. Whould anybody clear explay me difference and usage of these 3 commands (particulary in bash) : exec eval source I've tryed to read the manual pages but did not get much. Also could not get something useful from Google search - just so much and so not exactly, that is...

4. Programming

typedef struct forward declaration

I've google a bit about this and couldn't find an answer. Actually I read that it can't be done. Basically I've defined the following structure and typedef it as follows. stuct Name { }; typdef struct Name Name. and right after it, defined some API that use it. void blabla(Name*...

5. Programming

Need help with this c++ source code! DOnt understand what some stuff mean.

Okay so I am just starting programming c++. I just started started to red "C++ for Dummies yesterday and theres a lot of things I do not understand from this book and this source code especially. I will first post the full source code and then post questions about certain thing, usually what they...

6. Programming

typedef help

Hi! This is part of my my code : typedef struct{ int x; char na; char sur; } Stu; typedef struct{ Stu *arr; int size; int sort; } Stus; I want to ask how can i free() the matrix arr. I tried free(arr), free(Stus.arr) and i get errors with gcc. My problem, in...

7. Programming

Compilation problem with typedef

I am getting confused compiling a program that gives me the following error ../../../tomso/algeb/vector.hpp:19:9: error: �Vector' does not name a type typedef Vector<float> Vecflt;

8. Programming

Event driven programming / epoll / typedef union / session data array

Sorry for the �word salad� subject, but I wanted to cast a wide net for help. I've created an IP (Internet Protocol) server which serves HTTP, SMTP, and FTP requests. As you probably know, they all require creating a socket, listening on it, accepting connections, and then having a short...

9. Programming

Typedef does not work to name a type

Hello, This is related to the closed post in the forum for the installation of the same software called arachne, but with different error message: In file included from ueberal/MiniSuperizer.cc:5:0: ./random/GnuRandom.h:54:5: error: ‘_G_uint32_t’ does not name a type _G_uint32_t u; ^...

LEARN ABOUT DEBIAN

language::intercal::bytecode

INTERCAL::ByteCode(3pm) 				User Contributed Perl Documentation				   INTERCAL::ByteCode(3pm)

TITLE

       Language::INTERCAL::Bytecode - intermediate language

DESCRIPTION

       The CLC-INTERCAL compiler works by producing bytecode from the program source; this bytecode can be interpreted to execute the program
       immediately; alternatively, a backend can produce something else from the bytecode, for example C or Perl source code which can then be
       compiled to your computer's native object format.

       The compiler itself is just some more bytecode. Thus, to produce the compiler you need a compiler compiler, and to produce that you need a
       compiler compiler compiler; to produce the latter you would need a compiler compiler compiler compiler, and so on to infinity. To simplify
       the programmer's life (eh?), the compiler compiler is able to compile itself, and is therefore identical to the compiler compiler compiler
       (etcetera).

       The programmer can start the process because a pre-compiled compiler compiler, in the form of bytecode, is provided with the CLC-INTERCAL
       distribution; this compiler compiler then is able to compile all other compilers, as well as to rebuild itself if need be.

       See the online manual or the HTML documentation included with the distribution for more information about this.

SEE ALSO

       A qualified psychiatrist

AUTHOR

       Claudio Calvelli - intercal (whirlpool) sdf.lonestar.org (Please include the word INTERLEAVING in the subject when emailing that address,
       or the email may be ignored)

perl v5.8.8							    2008-03-29						   INTERCAL::ByteCode(3pm)