Undefined reference to Scalar::Scalar()

Question

I want to call function from class but it show me error. my test.cxx file is

#include<iostream>
#include"Scalar.hxx"
using namespace std;
int main()
{
    Scalar Text;
    char a;
    a=Text.SetBank(1);
    cout<<("%x",a);
    return 0;
    }

it show me error

undefined reference to `Scalar::Scalar()'
undefined reference to `Scalar::SetBank(char)'

Scalar.hxx

#ifndef __SCALAR_HXX__
#define __SCALAR_HXX__
#include <stdint.h>
class Scalar
{
    public:
        Scalar(void);
        char SetBank(char bank_no);
};
#endif

i have included correct file name.

Some questions: Are the files in the same folder? Do you get any warnings? Show full compiler output if you have not. What is your compilation line? — kabanus, Feb 13 '20 at 06:54
You have to compile the source file that defines the `Scalar` class (`Scalar.cxx`?) and link that object file with your program. Including the header allows your code to compile to object file — it doesn't ensure that the object code for the class is available when your program is linked. — Jonathan Leffler, Feb 13 '20 at 06:54
Can you show us the commands you are using for this? Both for compiler and linker, and any make file if there is one? — Tanveer Badar, Feb 13 '20 at 06:59
no i just run it using g++ text.cxx command,i also don't have any warnings. — unknowndeveloper, Feb 13 '20 at 07:04

score 0 · Answer 1 · answered Feb 13 '20 at 06:59

0

I do not think this is a compiler error in itself. Compiler is finding the definition just fine, but your linker cannot find the object files which contain the compiled code for Scalar and hence complains.

I have also commented requesting more data to help you with resolving this.

answered Feb 13 '20 at 06:59

Tanveer Badar

5,438
2
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i also think the same. how can i solve this error – unknowndeveloper Feb 13 '20 at 07:07
You mentioned you ran this command `g++ text.cxx`. Assuming `Scalar`'s implementation is in a file named Scalar.cxx, can you try the modification `g++ text.cxx Scalar.cxx`? – Tanveer Badar Feb 13 '20 at 07:08
ok i will try both file to compile at one time,or should i create makefile for it. – unknowndeveloper Feb 13 '20 at 07:15
For figuring out what the issue is, go without creating a make file for now and see what happens. – Tanveer Badar Feb 13 '20 at 08:14

score 0 · Answer 2 · answered Feb 13 '20 at 07:10

0

Scalar.hxx provides declaration for Scalar and SetBank methods but I see no definition. Is there Scalar.cxx file containing the code like the following?

Scalar::Scalar() {
    // ctor's body
}

char Scalar::SetBank(char bank_no) {
    // method's body
}

If there is then does it get compiled (i.e., included in your project/makefile)?

answered Feb 13 '20 at 07:10

PooSH

601
4
11

yes i have scalar.cxx file – unknowndeveloper Feb 13 '20 at 07:12
Then run `g++ scalar.cxx test.cxx` – PooSH Feb 13 '20 at 07:19

Undefined reference to Scalar::Scalar()

2 Answers2