Program Error Visual Studio

Question

I have this error in visual studio, and i dont know what does mean
Link for picture for the error https://ibb.co/FswnRmj

[code]

include <ostream>

include <string>

include <istream>

class Stock {

int code;
std::string name;
double valuePerUnit;
int noUnits;

public:
Stock();

Stock(int c, std::string n, double v, int nu);

void setCode(int c);

void setName(std::string n);

void setValuePerUnit(double v);

void setNoUnits(int n);

int getCode();

std::string getName();

double getValuePerUnit();

double getNoUnits();

double calcAmount();

friend std::ostream & operator<<(std::ostream &out, const Stock &s);

friend std::istream &operator>>(std::istream &in, Stock& s);

};
[/code]

[/code]

include "Stock.h"

include <iostream>

Stock::Stock() {
code = 0;
name = "";
valuePerUnit = 1;
noUnits = 1;
}
Stock::Stock(int c, std::string n, double v, int nu)
{
code = c;
name = n;
valuePerUnit = v;
noUnits = nu;
}

void Stock::setCode(int c)
{
code = c;
}

void Stock::setName(std::string n)
{
name = n;
}

void Stock::setValuePerUnit(double v)
{
valuePerUnit = v;
}

void Stock::setNoUnits(int n)
{
noUnits = n;
}

int Stock::getCode()
{
return code;
}

std::string Stock::getName()
{
return name;
}

double Stock::getValuePerUnit()
{
return valuePerUnit;;
}

double Stock::getNoUnits()
{
return noUnits;;
}

double Stock::calcAmount()
{
return getNoUnits() * getValuePerUnit();
}

std::ostream& operator << (std::ostream &out, Stock &s)
{
out << "\nCode : " << s.getCode();
out << "\nName : " << s.getName();
out << "\nNumber Of Units : " << s.getNoUnits();
out << "\nCost of Unit : " << s.getValuePerUnit();
out << "\nTotal : " << s.calcAmount() << std::endl;

return out;

}

std::istream& operator >> (std::istream& in, Stock& s)
{
std::cout<<"Enter Stock Code ";
in>>s.code;

std::cout<<"Enter Stock Name ";
in>>s.name;

std::cout<<"Enter value per Unit : ";
in>>s.valuePerUnit;

std::cout<<"Enter Number of Units : ";
in>>s.noUnits;

return in;

}
[/code]

Answer 1

Hi, @Galq Dimitrova
Error:

friend std::ostream & operator<<(std::ostream &out, const Stock &s);  

std::ostream& operator << (std::ostream& out, Stock&  s)  
{  
      out << "\nCode : " << s.getCode();  
      out << "\nName : " << s.getName();  
      out << "\nNumber Of Units : " << s.getNoUnits();  
      out << "\nCost of Unit : " << s.getValuePerUnit();  
      out << "\nTotal : " << s.calcAmount() << std::endl;  
      return out;  
}  

The declaration of the symbol isn't spelled the same as the definition of the symbol. Verify you use the correct spelling and capitalization in both the declaration and the definition, and wherever the symbol is used or called. You could refer to the document: Linker Tools Error LNK2019.

Best regards,

Minxin Yu

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Answer 2

I cut and pasted the questioner's code into an newly created empty VS2019 project (version16.11.5) and it compiled and linked without error.