Why can't I use outf in a function in C++

Question

I want to use outf in a function but when I try it show 'undefined' error.

I use visual studio 2013 and this is my code

int main(){

int costumer;
int d;
cout <<"Enter Number : ";
cin >> costumer;
d = costumer; 
int *Erand = new int[d]; //Random Number 1
int *Srand = new int[d]; //Random Number 2
int *SumArrays = new int[d]; // sum Array 
ofstream outf("Sample.dat");

//------------------------- Make Random Numbers

srand(time(0));
for (int  i = 0; i< d; i++)
{
    Erand[i] = 1 + rand() % 99;
}
for (int i = 0; i< d; i++)
{
    Srand[i] = 1 + rand() % 999;
}
//---------------------------- Out Put 
outf << "Random Number 1 " << endl;
for (int i = 0; i < d; i++) // i want it in a function
{
    outf << Erand[i];
    outf << ",";
}
outf << endl;

outf << "Random Number 2 " << endl;
for (int i = 0; i < d; i++)// i want it in a function
{
    outf << Srand[i];
    outf << ",";
}
outf << endl;
//--------------------------------calculator -------------------------
for (int  i = 0; i < d; i++)
{
    SumArrays[i] = Erand[i] + Srand[i];
}
outf << "Sum Of Array is : ";
outf << endl;
for (int  i = 0; i < d; i++)
{
    outf << SumArrays[i];
    outf << ",";
}
outf << endl;
delete[] Erand;
delete[] Srand;
delete[] SumArrays;}

for example i want use random number 1 in a function :

void Eradom(){
for (int i = 0; i < d; i++)
{
    outf << Erand[i];
    outf << ",";
}

but I got error in line 4.

Answer 1

outf is a local variable in your main function. To make it accessible to other functions you could either define it as a global variable (usually not recommended), or explicitly pass it to the Erandom function.

Answer 2

You define outf inside main() , but you try to access it inside the function Erandom() . That is causing this error. You must pass it to the function Erandom() as an argument.

Answer 3

Your outf variable is a local variable of main and thus not visible in your Erandom function. To pass the variable into your function, define it like

void Eradom(std::ostream &outf) {
  for (int i = 0; i < d; i++) {
    outf << Erand[i];
    outf << ",";
  }
}

And call it from main as

Eradom(outf);