Linking errors

[david188288]

Hi all,

This code cannot compile because of the following errors:

main.cpp|12|undefined reference to `Scheme::Scheme(std::string, short, short, short)'
main.cpp|15|undefined reference to `Scheme::parse_input(int, char**)'

I checked if the names matched, but the problem seems to lie somewhere else.
The relevant code is:

main.cpp

#include <iostream>
#include <string>
#include "error_manager.h"
#include "parser.h"
#include "filereader.h"

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

	// parameters which determine program running scheme
	Scheme param;

	// parse given input and initialize variables correctly
	param.parse_input(argc, argv);

	// attempt to read files, return error if failure occurs
	try {
			DataFile data = read_files(param.filename);
			std::cout << data.table[2][2] << "\n"; // test
			// run_prog(param, data);
	}
	catch (int e) {
			show_error(e);
			return e;
	}

	return 0;
}

parser.h

// manages parsing
#pragma once

#include <iostream>
#include <string>

class Scheme {

public:

	Scheme(std::string filename = "ta031", short pivot = 0, short neighbour = 0, short init = 0);

	std::string filename;
	short pivot;
	short neighbour;
	short init;

	// this will parse the received input
	void parse_input(int count, char* arg[]);

};

parser.cpp

// manages parsing
#pragma once

#include <iostream>
#include <string>


// struct for init data
class Scheme {

public:

	Scheme(std::string filename = "ta031", short pivot = 0, short neighbour = 0, short init = 0);

	std::string filename;
	short pivot;
	short neighbour;
	short init;

	// this will parse the received input
	void parse_input(int count, char* arg[]) {

		if (count<2) {
			std::cout << "Note that you can add arguments in the cmd\n";
			std::cout << "Check the help file for more information.\n";
		}

		else {

			for (int i=1; i<count; i++) {

				std::string str(arg[i]);

				if (str.substr(0,2) == "++") {
					filename = str.substr(2);
				}

				else if (str.substr(0,2) == "--") {

						 if (str.substr(2) == "first")	pivot=0;
					else if (str.substr(2) == "best")	pivot=1;

					else if (str.substr(2) == "transpose")	neighbour=0;
					else if (str.substr(2) == "exchange")	neighbour=1;
					else if (str.substr(2) == "insert")		neighbour=2;

					else if (str.substr(2) == "random-init")	init=0;
					else if (str.substr(2) == "neh")			init=1;

					else std::cout << "Warning: unkown parameter '" << str << "'\n";
				}

				else {
					std::cout << "Warning: invalid input '" << str << "'\n";
				}
			}

		}


	};

};

Does anyone see the error ?
Thanks

(this is compiled with gcc)

[ne555]

g++ -c *.cpp #compile
g++ *.o -o program.bin #link 

Instead of redeclaring your struct, just include the header.

//parser.cpp
//#pragma once //you would not include cpps
#include "parser.h"

void Scheme::parse_input(int count, char* arg[]) {
//...
}

Scheme::Scheme(std::string filename, short pivot, short neighbour, short init)://you never defined this
    filename(filename), 
    pivot(pivot), 
    neighbour(neighbour), 
    init(init)
{}

[david188288]

Thank you ! that was helpful.

just one more thing: in your code snippet, the compiler insists that:
parser.cpp|9|error: expected ')' before 'filename'

yet the code seems syntactically correct.
Any ideas why it shows an error ?

[Stewbond]

This is because filename is already a member of Scheme. You need to use a different name. I like to put a '_' in front of the variable name in my function argument list.

//parser.cpp
//#pragma once //you would not include cpps
#include "parser.h"

void Scheme::parse_input(int count, char* arg[]) {
//...
}

Scheme(std::string _filename = "ta031", short _pivot = 0, short _neighbour = 0, short _init = 0):
    filename(_filename), 
    pivot(_pivot), 
    neighbuor(_neighbour), 
    init(_init)
{}

[ne555]

No, that shouldn't matter. It is not in any way ambiguous

I updated the post, it should work now.
I forgot the Scheme:: at the beginning, that tells that it is a method of that class.
Also, default values can't be in declaration and definition. Prefer to put them in the header.

[david188288]

Thanks! that fix solved the error.