What is extern and how is it used?

I am not sure if the extern command is specifically C++ or C, but I know it work with C++. I see it used a lot in the q3 coding and wondered what it did. Thanks for the help.

extern specifies that the variable is in another file.

first it works with C and C++.

now as how to use it heres how

say you have a variable(int k = 10) in mycpp1.cpp and you want to use it in mycpp2.cpp use the extern to redeclare the variable and use it.

Example:

Code:

---

//mycpp1.cpp

int k = 10;

---

Code:

---

//mycpp2.cpp

extern int k;

void function(void)
{
    cout << k << endl;
}

---

this will print
10

Thanks! That solved the only problem I had with my app.