passing a vector of structs into a function

Question

In a program the following struct is defined in a header file:

\\structs.h
#include <vector>
using std::vector;
using namespace std;
struct cell
{
    double x;
    vector<int> nn;
};

In a separate source file I define the function:

\\functions.cpp
# define _CRT_SECURE_NO_DEPRECATE
# include <stdio.h>
# include <iostream>
# include <math.h>
# include <vector>
# include "structs.h"
using namespace std;

void initial_position(vector<cell>& cluster, int n)
{
    cell tmp;
    for (int i = 0; i < n; i++)
    {
        tmp.x = 1;
        cluster.push_back(tmp);
    }
}

with a header file:

//functions.h
# include <vector>
using std::vector;

void initial_position(vector<cell>& cluster, int n);

I wish to call this function in the main script:

//main.cpp
#define _CRT_SECURE_NO_DEPRECATE
#include <stdio.h>
#include <iostream>
#include <math.h>
#include <vector>
#include "functions.h"
#include "structs.h"  
using namespace std;

int main()
{   
    vector <cell> cluster;
    int n = 100;
    initial_position(cluster,n);
    return 0;
}

but get the following errors:

functions.h(4): error C2065: 'cell': undeclared identifier

functions.h(4): error C2923: 'std::vector': 'cell' is not a valid template type argument for parameter '_Ty'

functions.h(4): error C3203: 'allocator': unspecialized class template can't be used as a template argument for template parameter '_Alloc', expected a real type

main.cpp(14): error C2664: 'void initial_position(std::vector &)': cannot convert argument 1 from 'std::vector>' to 'std::vector &'

What is the source of the errors? it all seems to be well defined.

Answer 1

Put

#include "structs.h" 

into functions.h and protect both structs.h and functions.h with include-guards, eg

#pragma once

if available.

Answer 2

add

#include "structs.h" 

into functions.h since in functions.h compiler doesn't know what cell is.

Answer 3

Just swap

#include "functions.h"
#include "structs.h"  

with

#include "structs.h"  
#include "functions.h"

Since cell is declared in structs.h and is needed in functions.h

Or better yet, include structs.h in functions.h

You should also not place using namespace std in a header, that is bad practice. It can cause some nasty hard to find bugs, see eg Why is "using namespace std" considered bad practice?