'blah' was not declared in this scope, even though it was

[Adam Chance]

I'm trying to make a program which generates a random 4 digit number with new and delete.

Here is my code:

#include <iostream>
#include <cstdlib>

    using namespace std;

    int generate()
{
    int* pin;
    pin = new int[rand() % ( 9999 + 1 ) + 1000];
    
    cout << pin << endl;
}

    int question()
{
    string answer;
    cout << "Would you like to generate another PIN? Type 'yes' and press Enter to do so, or type 'no' or any other key and press Enter to close the program." << endl;
    getline (cin,answer);
    if(answer=="no")delete pin, pin = 0, return 0;
    if(answer=="yes")generate(), question();
    else return 0;
}

    int main(int, char**)
{
    generate();
    question();
    return 0;
}

When I compile this, GCC tells me:

main.cpp: In function ‘int question()’:
main.cpp:21:28: error: ‘pin’ was not declared in this scope
main.cpp:21:42: error: expected primary-expression before ‘return’
main.cpp:21:42: error: expected ‘;’ before ‘return’

I'm no C++ pro, so could one of you smart people help me out?

[Disch]

You need to understand scoping rules. when you declare a variable, it exists only inside of whatever braces it was declared in.

Here, 'pin' was declared in 'generate'. It does not exist inside of 'question'.

int generate()
{
    int* pin;
    pin = new int[rand() % ( 9999 + 1 ) + 1000];
    
    cout << pin << endl;
} // <- pin stops existing here.  Therefore:  memory leak 

Your code also does other questionable things. Are you trying to make thousands of ints? Because that's what you're doing.

Or did you mean to just make 1 int and set it to some 4 digit value? If that's the case then why are you bothering with new/delete at all? Why not just use a regular int?

Why do you have your functions returning an int when they don't return anything? Why not make them void?

etc

[Adam Chance]

I was testing new and delete.

It's not supposed to make thousands of ints.

I was focusing more on getting the code to compile rather than better code.

[Adam Chance]

The code is now:

#include <iostream>
#include <cstdlib>

    using namespace std;

    int* pin;
    pin = new int[rand() % ( 9999 + 1 ) + 1000];
    
    int generate()
{   
    cout << pin << endl;
}

    int question()
{
    string answer;
    cout << "Would you like to generate another PIN? Type 'yes' and press Enter to do so, or type 'no' or any other key and press Enter to close the program." << endl;
    getline (cin,answer);
    if(answer=="no")delete pin, pin = 0, return 0;
    if(answer=="yes")generate(), question();
    else return 0;
}

    int main(int, char**)
{
    generate();
    question();
    return 0;
}

GCC says:

main.cpp:7:5: error: ‘pin’ does not name a type
main.cpp: In function ‘int question()’:
main.cpp:19:42: error: expected primary-expression before ‘return’
main.cpp:19:42: error: expected ‘;’ before ‘return’

[TheCreator]

the first error refers to the fact that you are trying to output the whole array to ostream rather than a specific int. (pin isn't an int, its an array of thousands of ints)

Also put the consequences of if in brackets- its better practise and prevents errors

Also, question() will cause pin to display the same value of pin again if the answer is yes because you have defined the value of pin only once. Put the declaration of the value of pin in generate()
so basically put
pin= new int [rand() % (9999+1) +1000];
in generate()

finally i dont see the point of creating the array of ints, or is that just a mistake

[Nisheeth]

You should create one int. It should be :
pin = new int;
Then use pin = rand() % (9999+1) +1000; in generate.
You should also do this to make the generated numbers more random:
1.Include ctime header file.
2. In any one place add srand (time(NULL))
This will make the randomly generated numbers really random.