Question

I have a quick question regarding the scope of dynamic arrays, which I assume is causing a bug in a program I’m writing. This snippet checks a function parameter and branches to either the first or the second, depending on what the user passes.

When I run the program, however, I get a scope related error:

error: ‘Array’ was not declared in this scope

Unless my knowledge of C++ fails me, I know that variables created within a conditional fall out of scope when when the branch is finished. However, I dynamically allocated these arrays, so I cannot understand why I can’t manipulate the arrays later in the program, since the pointer should remain.

        //Prepare to store integers
        if (flag == 1) {
                int *Array;
                Array = new int[input.length()]; 
            } 
        //Prepare to store chars
        else if (flag == 2) {
                char *Array;
                Array = new char[input.length()];
            }

Can anyone shed some light on this?

Answer 1

Declare Array before if. And you can’t declare array of different types as one variable, so I think you should use to pointers.

int *char_array = nullptr;
int *int_array  = nullptr;

//Prepare to store integers
if (flag == 1) {
    int_array = new int[input.length()]; 
} 
//Prepare to store chars
else if (flag == 2) {
    char_array = new char[input.length()];
}

if (char_array)
{
    //do something with char_array
}
else if (int_array)
{
    //do something with int_array
}

Also as j_random_hacker points, you might want to change you program design to avoid lot’s of if