Question

I get a problem about pointer in C++. The code is:

int * initArray() {
    int a [2];

    a[0] = 1;
    a[1] = 2;
    return a;
}


int main () {
    int * b = initArray();

    cout << b << "---" << *(b) << endl;
    cout << b + 1<< "---" << *(b + 1) << endl;
}

The output is

0021FC20---1
0021FC24---1431629120

You can see that the value is wrong.

When I try to put the init array code into main function, it runs correctly.

Could you tell what wrong in my code?

Answer 1

initArray is returning the address of local array which ceases to exist after the function returns. This is an undefined behaviour.

To make the variable a persistent even when the function returns you can either:

• declare it as static
• make it global
• dynamically allocate it