How to fix ( 'vector' : undeclared identifier ) in my header file?

Question

I'm trying to create a function that calculates the average of all the numbers in my array. But when I run the code the vector in my header says its undeclared. What should I change ?

I have tried putting #include in my header file and using namespace std; but it still doesn't fix my problem. I have also tried passing my function as reference.

Source.cpp

#include <iostream> #include <string> #include "math.h" #include <vector> using namespace std; int main() { vector<int> notes; notes.push_back(8); notes.push_back(4); notes.push_back(3); notes.push_back(2); cout << average(notes) << '\n'; }

math.cpp

#include "math.h" #include <vector> using namespace std; int average(vector<int> tableau) { int moyenne(0); for (int i(0); i < tableau.size(); i++) { moyenne += tableau[i]; } return moyenne / tableau.size(); }

math.h

#ifndef MATH_H_INCLUDED #define MATH_H_INCLUDED int average(vector<int> tableau); #endif MATH_H_INCLUDED

You don't #include <vector> in math.h. Also prefer to explicitely state scope with std:: rather than using namespace std; — πάντα ῥεῖ
– πάντα ῥεῖ, Commented Apr 15, 2019 at 18:45
math.h is a C standard header. You should avoid using that file name for your header. — François Andrieux
– François Andrieux, Commented Apr 15, 2019 at 18:47

R Sahu · Accepted Answer · 2019-04-15 18:46:18Z

Add #include <vector>.
Use std::vector instead of just vector.
While at it, change the argument type to const&.

#ifndef MATH_H_INCLUDED #define MATH_H_INCLUDED #include <vector> int average(std::vector<int> const& tableau); #endif MATH_H_INCLUDED

Elro444 · Accepted Answer · 2019-04-15 18:45:49Z

0

You need to add #include <vector> in math.h instead of in math.cpp

answered Apr 15, 2019 at 18:45

Elro444

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3 Comments

Loïc Over a year ago

I have already tried that and it still gives me the same errors

Elro444 Over a year ago

That is because in math.h, you did not specify the namespace, so either write std::vector or add using namespace std; in the header itself

Loïc Over a year ago

Thanks I tried both #include <vector> and using namespace std; on their own instead of putting both at the same time dumb mistake.

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