Why is the output "0x7ffffcf9a010"?-CodePudding

#include <iostream>
#include <string>
using namespace std;

int main() {
    string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
    cars[0] = "Opel";
    cout << cars;
    return 0;
}

Why is it returning 0x7ffffcf9a010 when I output it?

CodePudding user response：

Yes, it will output that, the strange number you see is the address of the starting of the first element of the array, cars is implicitly converted to a pointer. By itself, it's an array rather than a pointer.

You want to do this,

#include <iostream>
#include <string>
using namespace std;

int main() {
    string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
    cars[0] = "Opel";
    //cout << cars[0]; // To print the first element
    for(int i = 0; i < 4; i  )
    {
        // To print all the elements one by one with a new line in between each element
        cout<<cars[i] << '\n';
    }

    return 0;
}

CodePudding user response：

Similar to raw array, output the name of it will return the first address of string array, here's an example.

#include<iostream>

int main() {
    std::string str[] = {"This", "is", "a", "string"};
    std::cout << str << std::endl;    //output 0xc3585ff5b0

    int arr[] = {1, 2, 3, 4, 5};
    std::cout << arr << std::endl;    //output 0xc3585ff590
    return 0;
}

CodePudding user response：

It outputs the hexadecimal address of the first element(0 index) of the array. Since array is a data structure that's why it outputs its address.

To correct the code you need to do this:

#include <iostream>
#include <string>


int main() {
    std::string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
    cars[0] = "Opel";
    
    char string1[100]={"C-style string."};
    std::cout << *cars<<"\n";
    
    
    std::cout<<string1; // does not show hexadecimal address but why?
    return 0;
}

Now this code will output 'Opel' as you required. The little asterisk next to the cars is known as the indirection operator. It is used to access the value the pointer is pointing to. Your confusion might be coming from the char array which can be outputted in one go using std::cout but the char array is an exception to the rule, the string array is not the same. Note(it is better use std::array and std::vector for modern C programming instead of the old fashioned array. )