I have a three files, Oracle.h, Oracle.dll, Oracle.lib.
These files are in same directory of main.c file.
And I want to include Oracle.h file.
#include <stdio.h>
#include "Oracle.h"
#pragma comment(lib, "Oracle.lib")
int main(void)
{
int crit;
char P[36] = { 0, };
char C[36] = { 0, };
int Clen = 36;
crit = Oracle(C, Clen);
printf("%d", crit);
return 0;
}
I used this code for main.c file, and compile by make main command.
But compiling this file has error, and I don't know what should I do.
$ make problem4_oracle
cc problem4_oracle.c -o problem4_oracle
/var/tmp/cc9oUwU3.o: In function main':
problem4_oracle.c:(.text+0x79): undefined reference to Oracle'
collect2: error: ld returned 1 exit status
<builtin>: recipe for target 'problem4_oracle' failed
make: *** [problem4_oracle] Error 1
Please help me.
Related
I am trying to make my first header file in C.
There are three files in same directory.
myHeaderFile.h
// It is a good practise to only declare function in header file.
int myHeaderFunction();
myHeaderFile.c
#include "myHeaderFile.h"
int myHeaderFunction()
{
return 1;
}
main.c
#include<stdio.h>
#include"myHeaderFile.h"
int main()
{
printf("main function.\n");
int output;
output = myHeaderFunction();
printf("%d\n",output);
return 0;
}
Cronology:
I created the first file myHeaderFile.h and saved it.
Then I created myHeaderFile.h and saved it.
Then, I created main.h and saved it. (I didn't run any of the file above'
I opened console and wrote the command as written below.
Then, I run main.h and it gave the error as mentioned below.
I open the console in the same directory and type:
gcc -Wall -o combined main.c myHeaderFile.c
It creates a file named combined.exe
And then I run main.c and it gives an error
undefined reference to `myHeaderFunction'
collect2.exe: error: ld returned 1 exit status
There are few answers for the error
undefined reference to `myHeaderFunction' but it involves too many function and files and gcc commands that I didn't understood as a begineer.
So I request not to close this answer and give a solution specific to this problem.
I am trying to compile a C file containing this code :
#include <stdio.h>
#include <stdlib.h>
#include <curl/curl.h>
int main()
{
curl_global_init( CURL_GLOBAL_ALL );
CURL * myHandle;
CURLcode result; // We’ll store the result of CURL’s webpage retrieval, for simple error checking.
myHandle = curl_easy_init ( ) ;
// Notice the lack of major error checking, for brevity
curl_easy_setopt(myHandle, CURLOPT_URL, "http://www.example.com");
result = curl_easy_perform( myHandle );
curl_easy_cleanup( myHandle );
printf("LibCurl rules!\n");
return 0;
}
,
Well when I try to compile :
gcc url.c -lcurl
I get the following errors:
F:\MinGW\home>gcc url.c -lcurl
C:\Users\Ehsan\AppData\Local\Temp\ccF7doFN.o:url.c:(.text+0x8e): undefined reference to `_imp__curl_global_init'
C:\Users\Ehsan\AppData\Local\Temp\ccF7doFN.o:url.c:(.text+0x95): undefined reference to `_imp__curl_easy_init'
C:\Users\Ehsan\AppData\Local\Temp\ccF7doFN.o:url.c:(.text+0xbf): undefined reference to `_imp__curl_easy_setopt'
C:\Users\Ehsan\AppData\Local\Temp\ccF7doFN.o:url.c:(.text+0xcd): undefined reference to `_imp__curl_easy_perform'
C:\Users\Ehsan\AppData\Local\Temp\ccF7doFN.o:url.c:(.text+0xdf): undefined reference to `_imp__curl_easy_cleanup'
collect2.exe: error: ld returned 1 exit status
I downloaded this distribution
and copied all files to bin, include , and lib folder.
What am I missing?
Update
Well I fixed the problem by using -lcurldll.
In my lib folder I have both libcurl.a and libcurldll.a.
Why linking with libcurl.a can't compile but with libcurldll.a it works fine?
You can check the lib name by:
readelf -d [LIB_PATH]
That would solve you the problem.
This question already has answers here:
Cuda C - Linker error - undefined reference
(2 answers)
Closed 7 years ago.
I'm new to CUDA programming hence running into issues with compiling/ linking files. I'm trying to compile .c and .cu files.
Here are the files:
p3.c:
#include <stdlib.h>
#include <stdio.h>
extern void load_scheduler(int k, int j);
int blocks, threads;
int main(int argc, char* argv[])
{
if (argc > 1)
{
blocks = atoi(argv[1]);
threads = atoi(argv[2]);
}
else
exit(1);
load_scheduler(blocks, threads);
}
And scheduler.cu file:
#include <stdlib.h>
#include <stdio.h>
__global__ void sched_func()
{
int j = 6*5*threadIdx.x;
printf("%d\n",j);
}
void load_scheduler(int b, int n)
{
sched_func<<< b,n >>>();
}
I compile these two files using nvcc -c scheduler.cu p3.c and it seems fine
However, when I try to link these two files using nvcc -o cuda_proj scheduler.o p3.o, I get an error:
p3.o: In function `main':
p3.c:(.text+0x58): undefined reference to `load_scheduler'
collect2: ld returned 1 exit status
I may not be using the right steps to get this working, so if there's any other way I should try out, suggestions are welcome. I am also new to making Makefiles so want to stick to using nvcc commands on terminal.
Just added : extern "c" before load_scheduler definition. NVCC could not recognize the function definition as it belonged to .cu file, therefore the error.
extern "C"
void load_scheduler(int b, int n)
{
sched_func<<< b,n >>>();
}
I created a program in C and I tried to compile it. When I use my gcc 4.8.1 compiler in Widows everything worked and my program too.
I compiled with the following arguments:
gcc -std=c99 -O2 -DCONTEST -s -static -lm children.c
But in linux I getting the following error:
/usr/lib/gcc/i486-linux-gnu/4.7/../../../i386-linux-gnu/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: error: ld returned 1 exit status
Why is that? My programm is working and I can't understand why I getting compiling errors in linux.
My code is:
/*---------------------*/
/* included files */
/*---------------------*/
#include <stdio.h>
#include <stdlib.h>
/*---------------------*/
/* defined constants */
/* for restriction */
/*---------------------*/
#define MIN 1
#define MAX 1000000
#define IOERROR 5 // 'Input/Output Error'
/*---------------------*/
/* function prototypes */
/*---------------------*/
int main();
FILE *read_input(const char *filename_r);
int count_children(FILE *input);
int pass_heights(FILE *input, int *children, int size);
int check_tall(const int *children, int size);
void write_output(const int total,const char *filename_w);
/*---------------------*/
/* start of program */
/*---------------------*/
int main() {
const char *filename_r = "xxx.in";
const char *filename_w = "xxx.out";
FILE *input = read_input(filename_r);
int size = count_children(input);
int *children = malloc(size * sizeof *children);
if (children==NULL)
exit(1); //General application error
pass_heights(input, children, size);
fclose(input);
int total = check_tall(children, size);
free(children);
write_output(total,filename_w);
return 0;
}
FILE *read_input(const char *filename_r) {
FILE *input = fopen(filename_r, "r");
if(input == NULL)
exit(IOERROR);
return input;
}
int count_children(FILE *input) {
int count = 0;
fscanf(input, "%d",&count);
if(count > MAX || count < MIN)
exit(1); //General application error
return count;
}
int pass_heights(FILE *input, int *children, int size) {
for(int i = 0; i < size; i++)
fscanf(input, "%d",&children[i]);
return *children;
}
int check_tall(const int *children, int size) {
int total = 0;
int tmp_max = 0;
for(int i = size - 1; i >= 0; i--)
{
if(children[i] > tmp_max) {
tmp_max = children[i];
total++;
}
}
return total;
}
void write_output(const int total,const char *filename_w) {
FILE *output = fopen(filename_w, "w");
if(output == NULL)
exit(IOERROR);
fprintf(output, "%d\n", total);
fclose(output);
}
You used -static option, which modifies the way executable is linked.
I was unable to reproduce your exact error message, but on my Linux it says that it is unable to link with -lc in static mode, and under my OSX it says that it is unable to locate -lcrt0.o. For me in both case, this means that the system is unable to locate the static stub.
If you remove -static it should work. If not, your problem is very strange.
The error you show indicates the linker is not finding the main() function in your code. As it is evident that you have included it in the source file, it is also evident you are not compiling with that command line (or you are compiling in other directory where you have a non-main() source called children.c, perhaps the build system makes a touch children.c if it doesn't find the source, and then compiles it --on that case it will not have a main() routine). Check that the files are properly created and where, as I think you aren't compiling that file anyway.
Try to use simple options before you go to more complicated ones. Try something like:
gcc -std=c99 -o children children.c
before trying to experiment with optimization or static linking anyway. Also, dynamic linking is normally better than static, so you'll get smaller executables (8Kb vs. 800Kb, and multiple copies of libc loaded per executable). Also, you don't need to include -lm as you aren't using any of the <math.h> functions (having it doesn't hurt anyway).
I have compiled your source with the following command line without any problem, but I do have support for statically linked executables and perhaps you don't (the command line I have put above would work in any linux, I suppose)
$ make CC='gcc' CFLAGS='-std=c99 -O2 -DCONTEST' LDFLAGS='-s -static -lm' children
gcc -std=c99 -O2 -DCONTEST -s -static -lm children.c -o children
children.c: In function ‘pass_heights’:
children.c:81:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
children.c: In function ‘count_children’:
children.c:69:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
Here is some code from Ben Straub's (link blog) that I am basing this on:
static int do_clone(const char *url, const char *path)
{
git_repository *repo = NULL;
int ret = git_clone(&repo, url, path, NULL);
git_repository_free(repo);
return ret;
}
And here is my code:
#include <git2.h>
int main(void) {
git_repository *out = NULL;
git_clone(&out, "https://github.com/lehitoskin/racketball", "/home/maxwell", NULL);
return 0;
}
I am very inexperienced with C, so I apologize for having such elementary problems. Anyway, here is the error my compiler gives me:
maxwell#max-pc ~ $ gcc -I libgit2/include gitfun.c
/tmp/ccB64nPh.o: In function `main':
gitfun.c:(.text+0x31): undefined reference to `git_clone'
collect2: error: ld returned 1 exit status
Why can't I call git_clone this way?
It looks like you didn't link to the library. Add -lgit2 if libgit2 is the lib name.
gcc -I libgit2/include gitfun.c -L<path to lib> -l<libname minus the "lib" part>
IOW, you compile fine but when the linker goes looking for git_clone it can't find it because you haven't specified the library that it is in.