Thread: Passing Vector as a Reference

I am having a problem passing a vector as a reference parameter and can not figure out why the program is not compiling or working. It is meant to read in text from a file, manipulate the vector into a new one, then print out the new one to a file. Everything is working except for the method that manipulates the vector. The syntax seems correct from reading several websites which is what confuses me. I have a header file but there is nothing wrong with it. Any hints are greatly appreciated!

Code:

#include <iostream>
#include <fstream>
#include <vector>
#include "hw1.h"

using namespace std;

int main() {
	int x;
	vector<int> first;
	vector<int> second;
	ifstream inFile;
	inFile.open("input.txt");
		while (inFile >> x) {
			first.push_back(x);
		}
		inFile.close();
		method(first, second);
		
	ofstream outFile;
	outFile.open("output.txt");
	for (int i = 0; i < second.size(); i++) {
		outFile << second[i] << endl;
	}
		outFile.close();
		return 0;
		
}

void method(vector<int>& x, vector<int>& y) {
	int step = 0;
	int j = 1;
	vector<int> temp(x.size() / 2);
	for (int i = 0; i < x.size() / 2; i++) {
		y[i] = x[step] + x[j];
		j+= 2;
		step+= 2;
	}
}

What doesn't work about it (assuming hw1.h contains a legitimate prototype of the function)?

hw1.h:8: error: variable or field âaddEven2OddLinesâ declared void
hw1.h:8: error: âvectorâ was not declared in this scope
hw1.h:8: error: expected primary-expression before âintâ
hw1.h:8: error: âvectorâ was not declared in this scope
hw1.h:8: error: expected primary-expression before âintâ
hw1prob2.cpp: In function âint main()â:
hw1prob2.cpp:15: error: request for member âpush_backâ in âfirstâ, which is of non-class type âstd::vector<int, std::allocator<int> >()â
hw1prob2.cpp:18: error: âaddEven2OddLinesâ was not declared in this scope
hw1prob2.cpp:22: error: request for member âsizeâ in âsecondâ, which is of non-class type âstd::vector<int, std::allocator<int> >()â
hw1prob2.cpp:23: warning: pointer to a function used in arithmetic


the header file is:

Code:

#ifndef HW1_H
#define HW1_H

template <class T>
void make2dArray(T ** &x, int numberOfRows, int rowsize[]);
template <class T>
void freeGen2dArray(T ** &x, int numberOfRows);
void method(vector<int>& x, vector<int>& y);

#endif

the method signatures match so they should not cause a compiling error.

No such thing as vector. There is such a thing as std::vector, though.

Thank my for the advice about including <vector> in the header class regarding the method signature. I changed that one simple line and the program compiled perfectly and executed flawlessly. C++ is so different in many aspects from Java but so similar in others.