Currently trying to build a project in eclipse. The project explorer is shown below:
In cabbie.c I get the error, undefined reference to initialize..., in the code below:
#include <stdio.h>
#include <stdlib.h>
#include "../iotfclient.h"
Iotfclient client;
int rc;
int main() {
/* Setup your example here, code that should run once
*/
rc = initialize(&client, "h7dzt2", "Edison_cabquam", "notwindows95", "token", "Over_9000");
/* Code in this loop will run repeatedly
*/
for (;;) {
}
return 0;
}
The function is already defined in iotfclient.h which was included as a header file. Is it correct to define it as ../iotfclient.h? Am I supposed to make a Makefile? The function prototype in iotfclient.h is given below:
int initialize(Iotfclient *client, char *orgId, char *deviceType, char *deviceId, char *authmethod, char *authtoken);
/**
* Function used to initialize the IBM Watson IoT client using the config file which is generated when you register your device
* #param client - Reference to the Iotfclient
* #param configFilePath - File path to the configuration file
*
* #return int return code
* error codes
* CONFIG_FILE_ERROR -3 - Config file not present or not in right format
*/
This project is trying to connect the bluemix IOT Platform.
initialize() is declared in iotfclient.h. However, it's not necessary defined. In other words, the compiler knows identifier initialise stands for a function, but to create a program, you have also to tell the linker how the function works, that is, add the function body.
Try including ../iotfclient.c.
The function initialize is declared in ../iotfclient.h, it might be defined in ../iotfclient.c, but do you compile this file and link it to your project?
Related
Hello I am working on a small roboter project at uni and I have run into following issue.
I have a typedef called RoboterData inside of a header file because I want to make use of it across multiple files. Inside of the main file I have a RoboterData data variable which holds important data.
My goal is to have access from other files to this data having the ability to get and set it from another file. I want to avoid the use of a global variable.
Here are the relevant code fragments of my approach:
main.h
typedef struct {
DriveMode mode;
short sensor_left;
short sensor_mid;
short sensor_right;
int left_eng_speed;
int right_eng_speed;
} RoboterData;
main.c
# include "motors.h"
// The Data I want to get and set from other files.
RoboterData data;
// Call to a funcion defined in motors.c
drive_straight(RoboterData *data);
motors.h
void drive_straight(RoboterData *data);
motors.c
# include "main.h"
enum {
ENG_STILL = 0,
ENG_SLOW = 50,
ENG_MID = 155,
ENG_FAST = 200
}
void drive_straight(RoboterData *data) {
data ->left_eng_speed = ENG_FAST;
data ->right_eng_speed = ENG_FAST;
set_duty_cycle(LEFT_ENG, ENG_FAST);
set_duty_cycle(RIGHT_ENG, ENG_FAST);
}
When I later try to print out the values left_eng_speed and right_eng_speed via serial port it stays at 0. I know C is call by value but since I am passing a ptr to my struct the value I am passing is the adress of the struct and when I dereference it via '->' I should be able to access its original data from my understanding and not a copy because the only thing I copied was the address.
If someone could explain to me why this is not working and provide a viable alternative, I would be very greatfull.
// Call to a funcion defined in motors.c
drive_straight(RoboterData *data);
This is a function declaration. It doesn't do anything. You want
drive_straight(&data);
to actually call the function.
I am using (Unicode) Inno Setup 6.0.5 on Windows 10 64-bit.
The exported symbol, I want to use has the signature:
typedef int(__stdcall *GetDirVST2x86) (LPWSTR lpString1);
The Inno Setup [Code] section has its declaration as:
function GetDirVST2x86(var lpString1: String): Integer;
external 'GetDirVST2x86#files:R2RINNO.DLL stdcall setuponly';
where, lpString1 will contain a pointer to the wide-string after the function returns and R2RINNO.DLL is a 32-bit DLL.
Now my problem is, if I compile and run this setup, a read access violation occurs right when I try to retrieve the value. I get the correct result when I execute this same function from a C program. Removing the var from the prototype declaration in Inno script fetches an empty (or possibly) empty or blank string, so that doesn't help either.
I don't have the source for the DLL I wish to use, and I figured out the signature from IDA. The scripting engine Inno Setup seems hopelessly inadequate as it doesn't support pointers at all.
One interesting thing I observed was if I changed the type of lpString1 to Cardinal or Integer and used IntToStr to fetch the string I got the value of the directory in which the setup was getting created.
Here's a working C code:
#include <windows.h>
#include <stdio.h>
#define _UNICODE
#define UNICODE
typedef int(WINAPI *GetDirVST2x86) (LPWSTR );
int main() {
HMODULE hModule = LoadLibrary("R2RINNO.DLL");
if (NULL != hModule) {
GetDirVST2x86 pGetDirVST2x86 = (GetDirVST2x86) GetProcAddress (hModule, "GetDirVST2x86");
if (NULL != pGetDirVST2x86) {
LPWSTR lpszVST2x86;
pGetDirVST2x86(lpszVST2x86);
wprintf(lpszVST2x86);
}
FreeLibrary(hModule);
}
}
Here's the output:
C:\Program Files (x86)\Steinberg\VstPlugins
Here's the IDA screenshot of the function I want to use:
Pascal Script equivalent of the C declaration should be:
function GetDirVST2x86(lpString1: string): Integer;
external 'GetDirVST2x86#files:R2RINNO.DLL stdcall setuponly';
(i.e. no var, as it is an input character pointer argument).
Assuming the function contract is that you (as a caller) allocate a buffer and provide it to the function to be filled in, you should call the function like this:
var
Buf: string;
begin
{ Allocate buffer for the result large enough according to the API specification }
SetLength(Buf, 1000);
GetDirVST2x86(Buf);
SetLength(Result, Pos(#0, Result) - 1);
end;
See also How to return a string from a DLL to Inno Setup?
I want to use a dll-file in my C-Code, but are very confused about the syntax.
My Story: I made a simple function in Matlab ( f(x1,x2)=x1*x2 ), with the "Matlab Coder" I translated it to C-Code and generated an exe, I could run it from the terminal with arguments.Now I generated a dll instead of an exe and want to use the dll.
Since now I could not make Code explanations, I googled, make work for me. I look up Syntax in http://en.cppreference.com/w/ but for my surprise there wasn't even an entry for e.g. GetProcAddress or LoadLirbary.
Here is the C-Code in which I would like to use the dll:
#include <stdio.h>
#include <stdlib.h>
/*
* In my dream I would load the dll function here
* with something like Load(mytimes4.dll)
*/
int main(int argc, char *argv[]) {
double x1,x2,myresult;
//Load Arguments from Terminal
sscanf(argv[1], "%lf", &x1);
sscanf(argv[2], "%lf", &x2);
// Use and print the function from mytimes4.dll
myresult = mytimes4(x1,x2);
printf("%3.2f\n",myresult);
return 0;
}
After generating the dll, Matlab gave me the following folder:
"dll-folder" produced by Matlab
Can someone give me a most simple but complete Code that would work with my example? What files are needed (maybe .def or .exp)? Also for Explanations of the lines involved using the dll I would be gratefull. Or if not, you maybe have some background knowledge that makes the complex syntax reasonable.Thanks in advance!
System information: Windows 7 Pro 64, Matlab 64 2016b, gcc cygwin 64, eclipse ide.
With the link of thurizas I could solve my problem.
https://msdn.microsoft.com/en-us/library/windows/desktop/ms686944(v=vs.85).aspx
I copied the code from the side. Below you can see the code with additional comments of mine and with ,in my opinion, more clearly naming. Thus it is probably easier to use for beginners as I am.
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
/*Declaration of the function,contained in dll, as pointer with the arbitrary pointer name
"*MYFUNCTIONPOINTER" (not sure if it has to be in big letters).
In my case the function means simply f(x1,x2) = x1*x2 and is thus as double declared*/
typedef double (*MYFUNCTIONPOINTER)(double, double);
int main() {
HINSTANCE hinstLib;
//"myfunction" is the arbitrary name the function will be called later
MYFUNCTIONPOINTER myfunction;
BOOL fFreeResult, fRunTimeLinkSuccess = FALSE;
//Tell the dll file
hinstLib = LoadLibrary(TEXT("mypersonal.dll"));
if (hinstLib != NULL)
{
/* At this line "myfunction" gets its definition from "MYFUNCTIONPOINTER"
and can be used as any other function.The relevant function in the dll has
to be told here.*/
myfunction = (MYFUNCTIONPOINTER) GetProcAddress(hinstLib, "mydllfunction");
// If the function address is valid, call the function.
if (NULL != myfunction)
{
fRunTimeLinkSuccess = TRUE;
// The function can be used.
double myoutput;
myoutput = myfunction(5,7);
printf("%f\n",myoutput);
getchar();
}
// Free the DLL module.
fFreeResult = FreeLibrary(hinstLib);
}
// If unable to call the DLL function, use an alternative.
if (! fRunTimeLinkSuccess)
printf("Message printed from executable\n");
return 0;
}
Creating a simple server-client program using rpcgen.
I'm writing this .x file:
program REMOTE_PROG {
version MSG_RCV {
int STRLEN(string) = 1;
double SQUARE(double *) = 2;
int NUM_OF_DEV(int *) = 3;
} = 1;
} = 99;
executing with rpcgen file.x -> generates file_svc.c.
in the file_svc.c file, for some reason, it generates each function case with _svc extension:
case STRLEN:
xdr_argument = xdr_wrapstring;
xdr_result = xdr_int;
local = (char *(*)()) strlen_1_svc; //<--_SVC
break;
and when I try to compile the server after implementing the functions
int * strlen_1(char **, CLIENT *);
the compiler raises that error:
"_strlen_1_svc", referenced from:
_remote_prog_1 in file_svc-8501b7.o
ld: symbol(s) not found for architecture x86_64
But if I'll delete that auto generated _svc extension,local = (char *(*)()) strlen_1; //no _svc the program will compile successfully.
Why does this happen? why does the rpcgen adds the _svc extension to the functions and am I doing something wrong when I delete the _svc?
P.S same error also for square and num_of_dev functions, gave only strlen for example.
Thanks!
That's the convention, the _svc is short for service.
Your server needs to implement the service function, that is the strlen_1_svc function.
Your client calls the strlen_1 function. rpcgen + the RPC library does all the inbetween - it generates code for strlen_1 used by the client which will serialize the data and transfer it to the server, where an event loop dispatches the call to your code in the strlen_1_svc function.
After execution of rpcgen ex7.x you should have created the client and server stubs ex7_clnt.c and ex7_svc.c and also a header file ex7.h
In the header file you will have declared both functions strlen_1 and strlen_1_svc, they have to have different names as they are different functions: first one is on the client side and invokes the second one on the server side through RPC call.
I'm trying to write a simple script using the FreeType library. The segfault is occurring during execution of the FT_Set_Pixel_Sizes method, though I'm using it correctly. Any help would be great. Here's the full code:
#include <ft2build.h>
#include FT_FREETYPE_H
main() {
FT_Library library;
FT_Face face;
FT_GlyphSlot slot;
FT_UInt glyph_index = 30;
char* font_file = "/usr/share/fonts/truetype/freefont/FreeMono.ttf";
// Render font
FT_New_Face(library, font_file, 0, &face);
FT_Set_Pixel_Sizes(face, 0, 16); /* THIS LINE IS CAUSING THE SEGFAULT */
slot = face->glyph;
FT_Load_Glyph(face, glyph_index, FT_LOAD_DEFAULT);
FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL);
}
You did not initialize your Library variable : see FT_LIBRARY documentation. You should use FT_Init_FreeType :
FT_Init_FreeType
Defined in FT_FREETYPE_H (freetype/freetype.h).
FT_EXPORT( FT_Error ) FT_Init_FreeType( FT_Library *alibrary );
Initialize a new FreeType library object. The set of modules that are
registered by this function is determined at build time.
output alibrary A handle to a new library object.
return FreeType error code. 0 means success.
You could first get used to this library following this tutorial. Take care to check the return values too ...
You have not initialized your library.
FT_Library library;
error = FT_Init_FreeType(&library);
if (error) { /* report error and exit */ }
You also have to check return values of functions like shown above. For instance, FT_New_Face returns an error (as it probably does in your case), you must not access face because it is left in an undefined state.