Programming :: Memory Allocate In Function And Call It By Reference For Array Structure?
Jul 2, 2011
I am writing a function(in C language in Linux) to initialize an array of a structure from a mysql table by calling a function by reference but I have a problem with call this function by reference . this is my program:PHP Code:
I am trying to add some function to the c++ project (calling function) and the called function are in C. And i am getting error "undefined reference to "Hello(int,int)" " while linking. It is compiling correctly. It is linking to header file mention in the calling function. This header file has definition to the c - called function. Do you thinking having c files into C++ project will be a problem? Should I remove <stdio.h> in c files?
I am currently writing a program using raw sockets. This program is used to send out ARP reply frames. The problem that I have is that I do not seem to be able to fill out a structure that is pointing to part of a character array.
Whilst I can fill out the variables of eth, I cannot fill out the variables of arp. If I fill them out and then send the contents of the array using send to, only the first structure (the ethernet header) is sent out. The rest of the data appears to be the original junk data in the array. I have checked the address of the structure pointer and it is pointing to the right place in the array. If I write a raw sockets program that uses an IP header struct and TCP header struct I can point these into the array and write to both of them without any issues.
The difference here is that the call to socket is different: Code: /* For ethernet */ fd = socket(AF_INET, SOCK_PACKET, htons(ETH_P_ARP)); /* For IP */ fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
If I just create one structure containing all of the variables needed this gets around the issue, however, I would like to know what I am doing wrong in the first instance.
I went to an interview last week and there was this guy who asked a simple question that i have been trying to solve for a couple of days. I tried google but i just cant get the search keywords right. The result were just useless. Well, the question is : "How can we allocate a limited memory to a process before we start its execution" well, the question is related to an X11 system so may be some flags must be set to limit its memory.
I am developing a code where I need to store the planes of an object in a tree & also i need to store it in a list for further processing ... when I try to allocate using malloc the memory allocation when i checked this in internet , I came to know that it may because the memory that I am trying to allocate may be more than the size_t variable.
I'm trying to create a program from 2 files - main.cpp that contains the main function, and modules.c that contains the definitions of the functions that are called in main(). modules.c only contain function definitions, no main function.
My Makefile is as follows:
I have included "modules.h", which contains all the function declarations, in my main.cpp.
When I try to make using this Makefile, I get the error
If I switch the order of modules.o and main.o in my $(TARGET) line, then I get errors that say "undefined reference to" the functions I have defined in modules.c, in main.cpp.
I am implementing c program to access ext3 file system's metadata. I want to know how to access members of the in-memory superblock structure. I am able access on-disk ext3_super_block structure but dont know how to access in- memory structure and its members.
I have a mxn matric (which is my simplified way of saying it is RAM with bytes on it) Some of the locations on this metric is filled with some data and some places are empty. The mxn are very big numbers in size. I am trying to make a program so that if a system call wants to write some thing on empty locations on this mxn metric it should be able to do so without any problem. The thing which I want to understand or logic of a data structure is what data structure do you people feel should I be maintaining so that I can allocate the requested space immediately from the above mxn matric when some system call requests for some (k) number of locations from above metrics.
The logic initially I thought was to maintain a hashtable
1bytes requested----------> location 1,location 2,location 3.........location n 2bytes requested----------> location 1,location 2,location 3.........location n 3bytes requested----------> location 1,location 2,location 3.........location n
but the problem with above logic is size of the pointers where I will be writing this problem is unsigned 64 byte.So to know location of one free byte if I am maintaining one pointer of type u64 this is not a feasible solution.
I have a script which takes an array as an input to the file.ex: test.ksh -l <array_value>
Every time I dont get the same array name.EX: test.ksh -l x ; where x="a b"test.ksh -l y ; where y="c d"
I store the value I get in l in varaible myLvalue.Now indise my Script I want to run a for loop for thevalue I get in -l.If I write the for loop as below. I'm getting value x.However I'm expecting the loop to run for a and b.
I am trying a scenario for calling a shell script when ever a trigger is called. Can some one guide me how to achieve this scenario. Also it should passes the value from the table to the shell script. Can some one explain me along with the example.
I'm looking for a way to launch "TRIM" commands to a SSD drive myself, from a c++ code I'm going to write, for flash erasing an SSD drive (and not to wait for others things that "should do it automatically in some circumstances if this or this, this and this have been enabled and [..]" but will never tell me if it worked or not
I know there is thousands of complicated ways to test and check if it worked, and also software that needs money to do so, that's why I just want to call myself the TRIM functions and read the return value (like true or false) in order to know if it worked !
Where I can find the c++ call that could permit me to do so ? I heard about the GLibC that gives a way to access every user space function related to Linux Kernel (poll, select and others) as standard c++ functions, I suppose that, if there is a way, it will be on the GLibC but how to find it ?
$1 is an argument which is actually and array. In function we want to assign a value 0 of it's first content. But it's wrong way. Anybody know the right way to assign value in function by passing as argument.
I'm trying to implement a solver for a system of differential equations in Fortran. The solver contains a number of functions which are supposed take real values, 1D arrays of real values or both as arguments and return arrays of real numbers, all of which cause the program to segfault. Example:
function y_exakt(t) implicit none real::t, pi
(the last number in the array seems to change randomly). Then the program crashes either when f(t,y) is called or when dy is returned (after removing the call to f). What could cause these (memory?) problems and/or what could I do to identify the problem? Increasing the maximum stack size with ulimit or compiling the program with -fno-automatic has had no effect. I'm using gfortran (gcc 4.4.3) on a 64-bit Ubuntu Lucid machine. The complete program can be found at [URL].
I need to call a function that takes a string array as argument, declared like this:Code:int someFunction(/* some parameters... */, const char* s);I'd like to know how to allocate memory for the string array. I know a string is an array of chars and an array is a pointer to the first element, then a string array should simply be a two dimensional char array. But is it a single memory block where all strings are stored consecutively?? Or is it a base vector where each element is a pointer to a separate memory block that contains a single string?More specifically: should I malloc() a single memory block large enough for all the strings? or should I allocate separate blocks for each string plus an extra one for the base vector?
I am writing a game in C with SDL. I can successfully display one image on the screen and animate it. However, I am having a lot of issues getting the background to display using the same method. I was asking for help on SDL related forums, but I determined that the issue is not SDL related, and it is actually a pointer issue. However, I can't find where I'm going wrong.