CODEWITHSUNDEEP
c++
Michael Davis
Michael Davis

Reputation: 11

How do pointers to C-Strings work compare to pointers to arrays of different data types?

I am a student in a CompSci intro class and I have a very basic understanding of pointers in C++. I had noticed in attempting to complete an assignment that a character array / c-string uses pointers differently than other data types.

For example, please consider the following code I created:

#include <iostream>

using std::cout, std::endl;

int main()
{
    int inta[] = {1,2,3};
    int* p1 = inta;

    cout << "p1 = " << p1 << endl;
    cout << "*p1 = " << *p1 << endl;
    cout << "sizeof(p1) = " << sizeof(p1) <<
        ", sizeof(*p1) = " << sizeof(*p1) << endl;

    char stra[] = "Dog";
    char* p2 = stra;

    cout << "p2 = " << p2 << endl;
    cout << "*p2 = " << *p2 << endl;
    cout << "sizeof(p2) = " << sizeof(p2) <<
        ", sizeof(*p2) = " << sizeof(*p2) << endl;
    return 0;
}

The output of *p1 and *p2 are both the first value of the array. However, while the output of p1 is the pointer to the first element of inta (which tracks from online research), the output of p2 is the entire word "Dog". The sizes of p1 and p2 are the same, the size of *p1 and *p2 are 4 and 1 respectively. Is there something I am missing?

I am using Visual Studio Community 2022 and created a normal project.

Thank you, and I appreciate your help!

Upvotes: 1

Views: 56

Answers (1)

pm100
pm100

Reputation: 50180

  • p1 is a pointer to an int. *p1 is thus an int -> size = 4
  • p2 is a pointer to a char, *p2 is thus a char -> size = 1

passing a char pointer to an output operator (cout<< or printf etc) will keep reading chars until it reaches the null char at the end of the string

Upvotes: 1

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