tons of errors

[Manga]

vs2019 gives me lots of errors.

Here is my code...

#include <iostream>
#include <vector>

using namespace std;

class funV { 
	std::vector<int> v;

public:
	//default constructor
	funV() {
		v.push_back(0);
	}

	//constructor
	funV(std::vector<int>& vect) {
		v = vect;
	}

	friend ostream & operator << (ostream &os, const funV &vv);

};

ostream& operator<<(ostream &os, const funV &vv) {
	
	
	os << "hi";
	
	return os;
}

int main() {

	vector<int> v1 = { 1,2,3 };
	
	
	funV one(v1);
	

	cout << one;

	
	return 0;
}

It works in cpp.sh but vs2019 says 16 errors including this...

Error C2679 binary '<<': no operator found which takes a right-hand operand of type 'funV' (or there is no acceptable conversion)

[jonnin]

what errors? It works fine in the shell, and it looks fine (well, there is the funky indentation... but it looks correct anyway).

[Ganado]

Works on VS2017 but I don't have VS2019 installed yet.

What happens if you remove line 40, what errors do you get? Might as well post all the errors.

[z05DSL3A]

No errors with VS2019 on my box.

[Manga]

Sorry guys... My post was misleading. I am doing what you see above but with a header file. So here is my actual code...


header.h

#pragma once
#ifndef header_h
#define header_h

#include <iostream>
#include <vector>

class funV { 
	std::vector<int> v;

public:
	//default constructor
	funV() {
		v.push_back(0);
	}

	//constructor
	funV(std::vector<int>& vect) {
		v = vect;
	}

	friend ostream & operator << (ostream &os, const funV &vv);

	int max() {
		int m = v[0];
		for (int i = 1; i < v.size(); i++) {
			m < v[i] ? m = v[i] : m = m;
		}
		return m;
	}

	int min() {
		int m = v[0];
		for (int i = 1; i < v.size(); i++) {
			m > v[i] ? m = v[i] : m = m;
		}
		return m;
	}

	void say();
};

ostream& operator<<(ostream &os, const funV &vv) {
	
	//os << vv.v[0];
	os << "hi";
	
	return os;
}

void funV::say() {
	for (int i = 0; i < v.size(); i++) {
		std::cout << v[i] << " ";
	}
	std::cout << std::endl;
};

#endif  

main.cpp

#include <iostream>
#include <vector>
#include "header.h"

using namespace std;

//a function that takes a vector
int max(vector<int> &vect, int n) {
	return 1;
}

int main() {

	vector<int> v1 = { 1,2,3 };
	
	
	funV one(v1);
	one.say();
	cout << one.max() << " " << one.min();

	cout << one;

	
	return 0;
}

[Ganado]

First issue is that you should change header.h line 22 to
friend std::ostream & operator << (std::ostream &os, const funV &vv);

Same thing for line 43.

Second issue, less importantly, is that for portability if you ever #include header.h more than once, is to define the functions on line 43 and 51 inside a .cpp file instead of defining it in the header, otherwise you'll get multiple-definitions errors. (Alternatively, declare the functions as inline.).

[ne555]

> if you ever #include header.h more than once
to clarify

//main.cpp
#include "header.h"
#include "header.h" 

no problem as you have header guards

however

//main.cpp
#include "header.h" 

//foo.cpp (also part of your project
#include "header.h" 

will fail at linking time with «multiple definition of `funV::say()' and `operator<<'»


@OP: you stil didn't post the error messages

[Ganado]

Yep, thanks for clarifying that. Requires using the same header in multiple compilation units.

[Manga]

Thanks Ganado... adding std:: solved my problem.

And yes I will add another .cpp file to put the definitions in. Thank you again....

Here was the errors I was getting...

Severity Code Description Project File Line Suppression State
Error C2065 'os': undeclared identifier Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 43
Warning C4018 '<': signed/unsigned mismatch Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 26
Warning C4018 '<': signed/unsigned mismatch Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 34
Error C2143 syntax error: missing ';' before '&' Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 43
Error C4430 missing type specifier - int assumed. Note: C++ does not support default-int Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 43
Error C2059 syntax error: 'const' Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 43
Error C2143 syntax error: missing ';' before '{' Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 43
Error C2447 '{': missing function header (old-style formal list?) Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 43
Warning C4018 '<': signed/unsigned mismatch Project1 C:\Users\Quality\Documents\Visual Studio\Project1\Project1\header.h 52