asked on

undefined reference to `getopt(int, char const , char const *)'

Hi Experts World,
I am using getopt to parse command line argument in C++.
How i am using it is the code below. can anyone tell me why i am getting the error message:
=======ERROR MESSAGE =========
undefined reference to `getopt(int, char *const *, char const *)'
collect2: ld returned 1 exit status
make: *** [wc.out] Error 1

======== CODE ========
#include "wc.h"
#include <stdio.h>
#include <unistd.h>

extern char *optarg;
extern int optind ;
extern int optopt;
extern int opterr;
extern int optreset ;

int getopt(int argc, char * const argv[], const char *optstring);

int main( int argc, char *argv[])
{
wc w;

bool checkL = false;
bool checkT = false;
bool checkD = false;
bool checkC = false;
bool noArgument = false;

char * inputFile = NULL;
int ch;

while ((ch = getopt(argc, argv, ":l:t:d:c:")) != -1) {
switch (ch) {
case 'l':
checkL = true;
inputFile = optarg;
break;
case 't':
checkT = true;
inputFile = optarg;
break;
case 'd':
checkD = true;
inputFile = optarg;
case 'c':
checkC = true;
inputFile = optarg;
case ':':
if(optarg = NULL){
cout<<"file Name missing\n";
exit(1);
}
else noArgument = true;
case '?':
default:
cout<<"Invalid option specified: \n"<< optopt<<"\n";
w.helpMenu();
}
}
argc -= optind;
argv += optind;

ifstream f(inputFile);
.
.
.

van_dy

put

#include <getopt.h>

in the begining, the error shall go

hope this heps,
van_dy

komlaaa

ASKER

I tried that it give the error message below.
Note: i am using C++

> make
g++ -g -Wall -ansi -c main.cpp wc.cpp
main.cpp:4: getopt.h: No such file or directory
make: *** [main.o] Error 1

SOLUTION

stefan73

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van_dy

Well i just compiled this piece of code and it seems to compile nicely:

main.cpp
-------------

#include <iostream>
#include <unistd.h>

extern char *optarg;
extern int optind ;
extern int optopt;
extern int opterr;
extern int optreset ;

int getopt(int argc, char * const argv[], const char *optstring);

int main( int argc, char *argv[])
{

bool checkL = false;
bool checkT = false;
bool checkD = false;
bool checkC = false;
bool noArgument = false;

char * inputFile = NULL;
int ch;

while ((ch = getopt(argc, argv, ":l:t:d:c:")) != -1) {
switch (ch) {
case 'l':
checkL = true;
inputFile = optarg;
break;
case 't':
checkT = true;
inputFile = optarg;
break;
case 'd':
checkD = true;
inputFile = optarg;
case 'c':
checkC = true;
inputFile = optarg;
case ':':
if(optarg = NULL){
std::cout<<"file Name missing\n";
exit(1);
}
else noArgument = true;
case '?':
default:
std::cout<<"Invalid option specified: \n"<< optopt<<"\n";
}
}

std::cout << checkL << ' ' << checkT << ' ' << checkD << ' ' << checkC << '\n';
return 0;
}

avizit

can you compile the program given in

http://www.gnu.org/software/libc/manual/html_node/Example-of-Getopt.html

if that doesn't compile I guess there is something wrong with your system headers etc ( assuming you are on a GNU system that is )

komlaaa

ASKER

Thanks, but sorry i did not mention it is on UNIX using g++ compiler.
i tried the code above and it is giving me the error message:

crux:~/achille/temp> g++ myGetopt.cpp
/var/tmp/ccGa6epa.o: In function `main':
/var/tmp/ccGa6epa.o(.text+0x120): undefined reference to `getopt(int, char *const *, char const *)'
collect2: ld returned 1 exit status

Thanks.

stefan73

Did you check if getopt() actually exists in your system's API?

On Solaris 2.8 it's fine.

komlaaa

ASKER

1.) i did include #include <stdlib.h> but still.
2.) i did not check my system(UNIX) to see if it has getopt( ),
but the question is if not what should i do. Since i have to run this program on
this system.

Please help Experts!!!

Thanks,

komlaaa

ASKER CERTIFIED SOLUTION

ankuratvb

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