C ++ 64位计算机，显示32位堆地址

Question

I created a sample C++ program on a 64 Bit linux machine running on VMware Player over host machine as windows. The below is a class code.

        class operatorOverloadingTest{
            private:
                    int age;
                    char *name;
            public:
                    operatorOverloadingTest(int age){
                            this->age = age;
                            name = new char[10];
                            strncpy(name,"Indra",strlen("Indra"));
                    }   

                    void displayDetails(){
                            cout<<"My Name :"<<name<<endl;
                            cout <<"My age: "<<age<<endl;
                    }   
                    friend ostream & operator<<(ostream &out, const operatorOverloadingTest &myObj);
                    ~operatorOverloadingTest(){
                            delete name;
                            cout<<" \nDestructor getting called"<<endl;
                    }
    };

In my Main function, created object of class:
1. By using new operator.
2. Stack Object.

int main(){
    operatorOverloadingTest *oOT = new operatorOverloadingTest(10);
    operatorOverloadingTest oOT1(30);

I understand that, on 64-Bit machine, memory address are represented in 8 Bytes.

When I run the program using GDB, i see the below address:

p oOT
$1 = (operatorOverloadingTest *) 0x613c20
p &oOT
$2 = (operatorOverloadingTest **) 0x7fffffffe228
 &(oOT1.age)
$7 = (int *) 0x7fffffffe210
(gdb) p &(oOT->age)
$8 = (int *) 0x613c20

My question is, why does object allocated in heap shows a 32 bit address representation and the object on stack (oOT1) shows a 64 bit address representation though my operating System is 64 Bit? (Checked using uname -a).

Answer 1

My question is, why does object allocated in heap shows a 32 bit address representation and the object on stack (oOT1) shows a 64 bit address representation

When you look at 0x1234 , you know that the entity has at least 16 bits, but you can't tell whether it's 16-bit, a 32-bit, or a 64-bit entity, because GDB will not print leading zeros.

If you want to know how big some program entity is, try:

(gdb) print sizeof(oOT)
(gdb) print sizeof(&ooT)