g++ : can't link with a main executable file

Question

I'm developing an application using statistical attacks to crack wep keys.

When I compile with my makefile (above) I get this error :

ld: can't link with a main executable file 'execStatAttack' for architecture x86_64

clang: error: linker command failed with exit code 1 (use -v to see invocation) make: * [statAttack] Error 1

My project contain those files :

statAttack.cpp : contain the main function, uses files above
rc4.h + rc4.cpp : with those function

#include <iostream>
#include <stdlib.h>
#include <stdio.h
#include <vector

#ifndef RC4
#define RC4

using namespace std
int* rc4(int);
int random_byte();
vector<int> cipher_mess_seq (long, int);

#endif

bias.h + bias.cpp :

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <utility>
#include <fstream>
#include <vector>
#include <string>

#ifndef BIAIS
#define BIAIS

using namespace std;

typedef pair<int,double> IntegerDoublePair;
vector<IntegerDoublePair> get_bias (string, int);
int compareTo (double, double);
vector<IntegerDoublePair> get_all_biases(string);

#endif

and the makefile :

CC = g++
CFLAGS = -Wall -g
LDFLAGS = -lm 
EXEC_NAME_NAIVE = execNaiveAttack
EXEC_NAME_STATALGO = execStatAttack
OBJ_FILES_NAIVE = naiveAttack.o biais.o rc4.o
OBJ_FILES_STATALGO = statAttack.o biais.o rc4.o

naiveAttack : $(EXEC_NAME_NAIVE)

statAttack : $(EXEC_NAME_STATALGO)

$(EXEC_NAME_NAIVE) : $(OBJ_FILES_NAIVE)
   $(CC) $(OBJ_FILES_NAIVE) $(LDFLAGS) -o $(EXEC_NAME_NAIVE)

$(EXEC_NAME_STATALGO) : $(OBJ_FILES_STATALGO)
   $(CC) $(OBJ_FILES_STATALGO) $(LDFLAGS) -o $(EXEC_NAME_STATALGO)

%.o : %.cpp
   $(CC) $(CFLAGS) -o $@ -c $<

clean :
   rm -f $(OBJ_FILES_NAIVE) $(OBJ_FILES_STATALGO)

mrproper: clean
   rm -rf $(EXEC_NAME_NAIVE) $(EXEC_NAME_STATALGO)

this is my configuration (terminal) :

==> g++ --version

Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1

Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)

Target: x86_64-apple-darwin13.1.0

Thread model: posix

So i would like your help, to find out why this error appeared.

Thanks.

You have several typos in your source files, e.g. #include <vector and using namespace std - you will need to fix these and any other similar mistakes to have a chance of compiling the code. — Paul R
You should also probably stick to spelling bias bias instead of also using biais in some places. Is there more to the error than what you pasted? — Etan Reisner
thank you for responding @EtanReisner. these errors are not really in the files, copy mistakes. i've changed also biais (french spelling) by bias. but the thing is that, i can compile the project and get working executable file. i forgot to mention that this error is in OS X, and on linux i have another kind of error : too long to copy it here. but it compiles. — Souf
I finally founded the error, it was in my makefile, those lines **naiveAttack : $(EXEC_NAME_NAIVE) **statAttack : $(EXEC_NAME_STATALGO) because the executable was already generated, and another compilation was done after, so it generates this error, for more informations i can provide the new makefile, for those who has this type of error. thank you for help. PEACE ! — Souf

Tim Sylvester Tim Sylvester · Accepted Answer · 2015-07-25T03:06:15

This error usually means you're missing a -c when compiling a simple program, something like this:

%.o: %.c
    $(CC) $(CFLAGS) -o $@ $^
Program: main.o
    $(CC) $(LDFLAGS) -o $@ $^

What's happening is that the first rule is building main.o just like you asked, but instead of being an object file, it's actually the complete, compiled and linked program.

When the second rule tries to use it as an object file, the linker finds that it's not an object file at all and produces "can't link with a main executable file."

Obviously for a more complex program, one with multiple object files or with library dependencies, it would not be able to build an executable from just the one source file, so you'll get a different error and never get as far as the link rule.

The solution, of course, is to add -c to the first rule so that the first invocation only compiles and does not link, producing an actual object file.

%.o: %.c
    $(CC) $(CFLAGS) -c -o $@ $^

g++ : can't link with a main executable file

2 Answers