collect2: error: ld returned 1 exit status

Question

I used the following:

gcc -c -O4 ab_test.c

This worked and generated ab_test.o without error, but

gcc -o ab_test ab_test.o -lgsl -lgslcblas -lm

lead to error as:

**/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../lib64/crt1.o: In function `_start':
/home/abuild/rpmbuild/BUILD/glibc-2.18/csu/../sysdeps/x86_64/start.S:118: undefined reference to `main'
collect2: error: ld returned 1 exit status**

The code is ab_test.c is as under

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <gsl/gsl_rng.h>
#include <gsl/gsl_randist.h>


Main()
{
  int i, temp_int;
  char amode[30];
  char bmode[30];
  float wave_vector_y;
for(i=0; i<41; i++)
    {
        //// set wave vector ////
        wave_vector_y = i*0.005;    

        temp_int = 10000*wave_vector_y;
        sprintf(amode,"a%04d.dat",temp_int);
        sprintf(bmode,"b%04d.dat",temp_int);
    }
}

@πάνταῥεῖ but not `int main(void)`. The whole main should look like `int main(void){ ... return 0;}` — bitcell, Nov 18 '14 at 12:01
@UniCell No, you're wrong. It's OK to omit the `return 0;`. That's guaranteed to be the default for `main()`. — πάντα ῥεῖ, Nov 18 '14 at 12:03
@πάνταῥεῖ tell me you didn't said that. I hope that in the programs made by you there is a `return 0;`.How would you know that the program exit correctly? — bitcell, Nov 18 '14 at 12:05
@UniCell - it's your own styling technique. While I prefer to return a value from main, it is not required, and you could also use the C lib `exit(return code)` to specify an exit code for a void returning main entry point (I don't like it, but it's possible). — Moshe Gottlieb, Nov 18 '14 at 12:10
@iMoses (not exactly to `return 0`, but `return _something_`) and it's good practice. — bitcell, Nov 18 '14 at 12:11
@UniCell _"tell me you didn't said that"_ No, I'm telling you exactly that, and it's true for `main()`. Nothing hinders you to put a `return -1;` in case of an error there. But ***you can omit*** `return 0;`. As mentioned it's the default. — πάντα ῥεῖ, Nov 18 '14 at 12:11
@πάνταῥεῖ not exatly `return 0;` but `return something;` if you use `int main(void)` — bitcell, Nov 18 '14 at 12:14

score 0 · Answer 1 · edited Nov 18 '14 at 12:00

0

Your "main" signature should be something like int main(void)or int main(int argc ,char *argv[]) and not old C style syntax for int Main().

edited Nov 18 '14 at 12:00

David Ranieri

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answered Nov 18 '14 at 11:56

Moshe Gottlieb

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_"and not old C style syntax ..."_ ?!? Uhm what? – πάντα ῥεῖ Nov 18 '14 at 12:01
1

Old C style syntax doesn't allow `int Main()` – David Ranieri Nov 18 '14 at 12:01
Never said it is an acceptable signature, but not specifying the return type is old C style. – Moshe Gottlieb Nov 18 '14 at 12:02
@AlterMann - `char**` is perfectly valid for the main signature. – Moshe Gottlieb Nov 18 '14 at 12:05
Yes, `char **argv` and `char *argv[]` are interchangeable , but `int main(int,char**)` is not valid (variable names are omitted) – David Ranieri Nov 18 '14 at 12:16
@AlterMann - that's wrong. `int main(int,char**){ return 0; }` is a perfectly valid C++ program (but not C). – Moshe Gottlieb Nov 18 '14 at 12:20
@iMoses, oops, question is also tagged `C++`, sorry!! anyway `int main(int argc ,char *argv[])` is valid in both languages – David Ranieri Nov 18 '14 at 12:27

collect2: error: ld returned 1 exit status

1 Answers1