How to build a Lib

Kofr

#ifndef CALCLIB_H
#define CALCLIB_H

#if defined(CALCLIB)
#define CALCLIB_COMMON_DLLSPEC Q_DECL_EXPORT
#else
#define CALCLIB_COMMON_DLLSPEC Q_DECL_IMPORT
#endif
namespace CalcLib {
enum TypeWork : int {
    Addition,
    Subtraction,
    Division,
    Multiplication
};
enum ErrorCode : int {
    Div0 = -9,
    WrongTypeWork = -8,
    Ok = 0,
    OperandIsWorng
};
}

CALCLIB_COMMON_DLLSPEC double DoIt(int TypeWork, double OperandA, double OperandB, int& ErrorCode);


#endif // CALCLIB_H

#include "calclib.h"
#include <limits>



double DoIt(int TypeWork, double OperandA, double OperandB, int &ErrorCode)
{
    switch (TypeWork) {
    case CalcLib::Addition:
        ErrorCode = CalcLib::Ok;
        return OperandA + OperandB;
    case  CalcLib::Subtraction:
        ErrorCode = CalcLib::Ok;
        return OperandA - OperandB;
    case CalcLib::Division:
        if(OperandB == 0) {
            ErrorCode = CalcLib::Div0;
            return std::numeric_limits<double>::infinity();
        }
        ErrorCode = CalcLib::Ok;
        return OperandA / OperandB;
    case CalcLib::Multiplication:
        ErrorCode = CalcLib::Ok;
        return OperandA * OperandB;
    default:
        ErrorCode = CalcLib::WrongTypeWork;
        return 0;
    }
}

When building I get errors in this line
CALCLIB_COMMON_DLLSPEC double DoIt(int TypeWork, double OperandA, double OperandB, int& ErrorCode);
:-1: error: LNK2001: unresolved external symbol _WinMainCRTStartup

debug\src.exe:-1: error: LNK1120: 1 unresolved externals

D:\dev\testing\DumbCalc\calcLib\calclib.h:24: error: C2144: syntax error: 'double' should be preceded by ';'

D:\dev\testing\DumbCalc\calcLib\calclib.h:24: error: C4430: missing type specifier - int assumed. Note: C++ does not support default-int

Compiler is MSVC2015 x86
What do I do wrong? How to make it work.

SGaist

Hi,

Can you also show your .pro file ?

Kofr

@SGaist

TEMPLATE = lib
CONFIG += c++14 exceptions_off rtti_off
SOURCES += calclib.cpp
HEADERS += calclib.h
DEFINES += CALCLIB

the full project
https://www.dropbox.com/s/d3ttz06dtxrd2i6/DumbCalc.zip?dl=1

jsulm

@Kofr said in How to build a Lib:

CALCLIB_COMMON_DLLSPEC double DoIt(int TypeWork, double OperandA, double OperandB, int& ErrorCode);

Why do you name the first parameter same as your first enum (TypeWork) and same for ErrorCode?!
Don't you mean:

CALCLIB_COMMON_DLLSPEC double DoIt(CalcLib::TypeWork typeWork, double OperandA, double OperandB, CalcLib::ErrorCode &errorCode);

I can build your project after adding

#include <QtCore/QtGlobal>

in calclib.h