Programming :: C++ - Calling Functions From Other Files And Headers?
Apr 11, 2011
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'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.
How does a C program start in linux? Is main() the first function called in the a c application by kernel. I understand it is the first called function written by the application programmer, but the question is to understand the what all kernel does and what all functions it calls before calling main()
I have written FORTRAN code to calculate density profile. This code will open two files ( topology and x,y,z trajectory). The trajectory file contains XYZ data coordinates for multiple frames (about 20 or 100 frames for instance). One frame contains 20736 data.
Previously this code was written to open ONLY one input XYZ data file and do the calculation and would dump the results in separate file and it was running without problem. Recently my data file get bigger in size, so I decided to break the single XYZ data file into few small parts.
Now I have modified the code so that it calls the parts of the XYZ data files ( eg: maltoTHERMO_10Frames.traj, maltoTHERMO_20Frames.traj,... and so on) and do the calculation and dump the results in the same result output file. I have tested this code just with openning the XYZ coordinates and printing into another file to see wheather it collecting the data sequently and it was working fine.
This code supposedly read the x coordinate data and calculate distance and put a count accoding the criteria in the approperiate bins. But when I let the code to do the calculation it stop and shows error. (I have indicated as !** in the code). If I enable this line, it shows error but if I disable this line, than the code do collect only the XYZ coordinates.
I am trying to play with calling text files in C. What I have is a text file with 4 columns of numbers I need to average 2 of them. I have started and hit a wall. I have the following so far:
[Code]....
I still need to figure out how to read the data in. I have been reading on this for a few hours and its not clicking. How does the program know which columns with names to call. the data is organized: ID, Day, Speed, Temp.
I have several classes that I use for multiple programs. Where should I keep the h/cpp files so I only have to add the #include for the compiler to find them?
I wrote the following script to organize my music files and to learn a bit more about bash.
My problem is, now that I'm almost over the first version, that functions which are surely spelled correctly and were recognized in the past, are giving me the "command not found" error!
Code: #!/bin/bash # This is a script for moving tagged files into organized directory trees. ##### Variables filenum=0
I am learning network programming via a book of Richard Stevens.The sample source codes are given here http://www.unpbook.com/unpv13e.tar.gz I downloaded and unzipped the file in /usr/src folder.As per the instructions given in README of downloaded archive I did.
I have a question about calling an asm function from C....It doesn't work unless I create an asm variable to hold the value of the function in....Why?Here's the code that doesn't work...
asmfile.s - version one Code: .section .data mydata: .ascii "this is the message! .equ mylen, . - mydata
I am doing a web site program and what I need is to call a C program in the PHP cloud.Do u think it would be possible? The web site would get the user input from PHP UI and pass to the C program , the C program would process the function with the user input and output the a PHP page.
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 want to call c exe from java source code and i want to interact with the c program during it's execution, i am able to send the parameters to c program but i am not able to interact with it.
I have spent quite a lot of time on this problem. It seems like the file is sometimes closed when reaching config(fd), but removing the usleep(a while) seems to remove the problem.
I have a bash script that changes the iptables.Now i call this bash script in my php code.When this bash script is running the part of code that contains iptables instruction is not running because we need to be in superuser mode(root)
I'm trying to call some Fortran 95 code in C, but I'm having problems with integers not having the same value in C as in Fortran, and changing values upon each run of the program. I think it has to do with the integer type, but I don't know how to fix it. I'm running Gentoo x86. Here are the files I've got:
I'm trying to call a system command in perl and am having an issue with it.
Here's an example of a command i'd like to call: Code: sed -i '4 c192.168.1.4 www.something.com' hosts this is the section in my perl script where I create the variable and call it: Code: $doit = `sed -i '$line c$ip $host hosts'`system($doit); The $line, $ip, and $host variables are working fine becasue I can replace that section with "prints" and they come out fine. I imagine the problem is where I am creating the $doit variable.
I want to call a subroutine in Fortran 90 from a c++ code. I can do it, when the fortran code have no module. But i need to call the subroutine in a fortran code that have an module. I have a simple program that shows my problem. The Fortran code is:
collect2: ld returned 1 exit status I Dont know where is the problem. Maybe it is in the call of the function. I found that the syntax have this form: extern void __namemodule__NMOD_namesubrutine(arg)
I am trying to use a software package written in ANSI C. It has a makefile which has to be executed first.
As soon as I execute it I get messages like: line i: command not found.
Commands for which I am getting errors :
CC = /usr/bin/gcc GCCFLAGS = -c -Wall ROOTDIR = .
My gcc compiler is located in the above directory only. In ROOTDIR also I tried giving the path in which all the required files & folders are present but still I get the command not found error in all the lines.
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.
