Programming :: Wrapping Around Functions With Different Return Types?
Feb 1, 2010
I have functions which return different data like: int, char*, double...
I also have a list of datatypes (INTEGER, TEXT, REAL...) which can be returned.
I need to map a datatype with function, which purpose is to return it. Therefore, when I determine a datatype, I would like to call the required function without doing switch all the time.
I'm trying to use "netlink" to get ip address of a Linux box. But the linux/types.h included from "linux/rtnetlink.h" introduced many conflicting type declarations with "sys/types.h".
#include <rtnetlink.h> #include <sys/types.h> #include <sys/socket.h> int main (int argc, char *argv[]) { return 0; }
I would like port 80 to have a small daemon running on it that detects HTTP traffic and sends a small redirect response, and any other traffic begins streaming data from my VPN daemon. I was wondering if this has already been made, or any kind of technology for detecting types of traffic and allowing you to run multiple types of servers on the same port.
What are the different types of API's in linux?How can we predict the kind of API we are using?And what are API layers related to?Are API's and system calls ,both are same?
I guess I'm just a noob, but I notice that some C libraries (and even some C++ ones) tend to redefine the basic types with their own naming convention.
For example, OpenGL redefines the basic types: Code: from GL/gl.h typedef unsigned int GLenum; typedef unsigned char GLboolean; typedef unsigned int GLbitfield; typedef signed char GLbyte; typedef short GLshort; typedef int GLint; [Code].....
I decided to try making a programming language again after my last unsuccessful attempt, so now I figured how to write a good AST and it works great when the nodes are hard-coded into a test program. But to make a language out of it, I need a parser to build the tree according to an input file. I ran into a problem here:
%token SEMICOLON INTEGER VARIABLE IF WHILE DO OPAREN CPAREN OBRACE CBRACE %right ASSIGN %left NE %left PLUS MINUS %left TIMES DIVIDE %% .....
As you might see, each nonterminal creates a Node* object and uses it as its value. The problem is that the literal tokens, however, don't return Node*'s and I don't know what to do. I would like to be able to convert literal tokens to nodes in the Lex file (which would avoid the problem), but the problem is with the assignment operator, which takes a Node* for the right-hand side and a variable name (not a Variable Node, because they just evaluate the the variable's value and you can't change the variable with them) for the left hand side.
None of my daemon scripts work now, and the startup process displayed errors. Should I reinstall the OS and start from scratch, or is there a way to recover these files? Is there a way to rebuild the files I deleted?
I trying to write a UART(interfacing of serial devices) to linux machine but after I execute the following code to receive data I need to enter key (carriage return).... but I don't want to remove carriage return/enter key
Where are the definitions for C library functions located? It was just recently that I realized that header files don't actually define any functions, they merely include their prototypes.
For instance, stdio.h includes the following line:
Code:
This just means that the definition of printf() is located in another file. What file? Is there some kind of default shared object file that is automatically included during compilation?
I have problem to use an alias that defined in ksh93 script,in the functions in the same script onm Linux.I definied an alias in main: alias echo='echo -e' in order that echo will read backslashes but when i executed it in function, the alias didnt work, and performewd a regular echo, without -e
cat test.ksh #!/bin/ksh alias echo='echo -e' checkUsage
have an application where from time to time I need to check the db for some value and run some functions to do some checks. is the best option do it as php daemon or cron job?Whatworried of cron job is the overalapping.
Im implementing a chat application using Jabber/XMPP and gloox framework which should send and receive messages concurrently in Ubuntu Linux.
The problem faced is both the threads are created and pthread_join( ) is called for both.The iSend thread is scheduled first but gets suspended at cin. Once the recv( ) function is called, which runs in iRecv thread, the recv call back function handleMessage( ) is called. However the control never shifts back to the iSend thread which should call SendMessage( ) function.
I am trying to write a simple program in C that involves nesting switches. For example switch 1 offers an option to go to module 1 or 2 or quit. when I go to module 1 there is another switch function offering two or more choices.
I can select either module 1 or 2 at the start of the program and the selection text for, say, module 1 prints to screen but then exits without allowing a second selection to be entered.
I tried using free([first selection]) thinking that might do the trick but it doesn't.
Is it possible to next switches on after another in C?
But I would like to avoid this approach as there are a lot of places in my program where I would have to make this change. Can I perhaps rebuild the pthreads library on macos without affecting other apps ?
Let's show the problem: I have a socked connection (in a fd var). In certain moment, I need to use the same socket in two threads. Lets see in the example:
I feel like there should be a cleaner way of doing this. I have one file, for example "a.cpp", calling a function from another file, "b.cpp". Currently I have it set up so that header for "b", "b.h", has the declaration of its functions. And then I'm just including "b.h" in "a.cpp". Do I have to include the "b" header file in "a" to be able to call a function from "b"? Or is there a better way I could be doing this? Like doing something different at compile?
I've encountered a problem when running a simple bit of code, I'm using c to read write data to a binary file. It works fine when I run as root. However when I run as a user it produces the file, however when I try to open / write after it's produced it caused a seg fault. Is there any reason file functions ( fopen etc ) would work for root and not a user and is there a way to fix this?
I'm trying to call some kernel functions from userspace, but I'm not sure if I'm doing it right. The functions control a pulse width modulator on an embedded platform. To pick one at random, the function:
Code: struct pwm_device *pwm_request(int pwm_id, const char *label); is defined in linux/pwm.h, and the implementation uses the macro EXPORT_SYMBOL(pwm_request), so I should be able to call this from user-space... right?
Anyway, I've got linux/pwm.h to #include in my source so the compiler knows what it's doing, but what do I link against? The only place in by kernel build tree where I can see a symbol pwm_request defined is in object files like vmlinux.o, built-in.o in the directory, etc. which I don't think I should be linking against.
My distribution is Fedora 12. When I want to get the infos of kernel functions such as printk, i type man printk, failed. I look up some articles and learn that in some distributions the kernel functions is in section 9 of man page. Then i type man 9 printk also no reply. How can i get man pages of kernel functions ?
So if you are a PHP-programmer (average one) and code for money, how many of funtions and operators of PHP should you remember by heart (in real life)? I was looking through php.net and man there are millions of tons of them!
I have created a glade file which so far have two regions in it:
1) On the right division is a toggle button which calls a C script when enabled.
2) I have a drawing area, in which I would like to plot a point (X-Y scatter plot). The plot should be generated dynamically using a C script. I am not sure how the integration between the two is possible for a drawing area.
In glade what properties of drawing area should I set? eg.expose event, realize etc. I was thinking of using cairo for generating the plot.
