passing vector to function c++ - c++

Question

I have a main.cpp test.h and test.cpp> I am trying to pass my vector through so i can use it in test.cpp but i keep getting errors.
//file: main.cpp
int main(){
vector <Item *> s;
//loading my file and assign s[i]->name and s[i]-address
tester(s);
}
//file: test.h
#ifndef TEST_H
#define TEST_H
struct Item{
string name;
string address;
};
#endif
//file: test.cpp
int tester(Item *s[]){
for (i=0; i<s.sizeof();i++){
cout<< s[i]->name<<" "<< s[i]->address<<endl;
}
return 0;
}
---------------errors--------
In file included from main.cpp:13:
test.h:5: error: âstringâ does not name a type
test.h:6: error: âstringâ does not name a type
main.cpp: In function âint main()â:
main.cpp:28: error: cannot convert âstd::vector<Item*, std::allocator<Item*> >â to âItem**â for argument â1â to âint tester(Item**)â

Answer 1

A std::vector<T> and T* [] are not compatible types.
Change your tester() function signature as follows:
//file: test.cpp
int tester(const std::vector<Item>& s) // take a const-reference to the std::vector
// since you don't need to change the values
// in this function
{
for (size_t i = 0; i < s.size(); ++i){
cout<< s[i]->name<<" "<< s[i]->address<<endl;
}
return 0;
}
There are several ways you could pass this std::vector<T> and all have slightly different meanings:
// This would create a COPY of the vector
// that would be local to this function's scope
void tester(std::vector<Item*>);
// This would use a reference to the vector
// this reference could be modified in the
// tester function
// This does NOT involve a second copy of the vector
void tester(std::vector<Item*>&);
// This would use a const-reference to the vector
// this reference could NOT be modified in the
// tester function
// This does NOT involve a second copy of the vector
void tester(const std::vector<Item*>&);
// This would use a pointer to the vector
// This does NOT involve a second copy of the vector
// caveat: use of raw pointers can be dangerous and
// should be avoided for non-trivial cases if possible
void tester(std::vector<Item*>*);

Answer 2

Pass it as std::vector<Item *> & (reference to vector) and use iterator to iterate through it.

Answer 3

You should #include <string>.
string name should read std::string name etc. Same goes for std::vector.
You're calling tester() with a vector, yet it expects an array (the two are not interchangeable).
s.sizeof() is incorrect for both an array and a vector; for the latter, use s.size() or, better yet, use an iterator.
These are just the errors that immediately jump out; there may be more.

Answer 4

A vector is not an array.
int tester(vector<Item *> &s)
(pass as a reference to avoid copying or if you need to modify)
You also need to modify your code inside the tester function to work correctly as a vector.

Answer 5

You should fix
test.h:5: error: âstringâ does not name a type
first, probably by using namespace std; and #include <string>

Answer 6

You are missing includes
#include <string>
#include <vector>
and you need to use std::string and std::vector<>. A std::vector is not an array, so you should pass the vector as reference
int tester(std::vector<Item*> & vec) { //... }
or even as const std::vector<Item*> & if you are not going to modify the passed vector.
Also, are you sure, that you'll need a vector of pointers? What are you trying to achieve?