what is wrong with this program?

Question

#include 
#include 
#include 

using namespace std;

int main() {
    string x;
    getline(cin,x);
    ofstream o(\"f:/demo         


        

Answer 1

You seem to have an incorrect model of sizeof, so let me try to get it right.

For any given object x of type T, the expression sizeof(x) is a compile-time constant. C++ will never actually inspect the object x at runtime. The compiler knows that x is of type T, so you can imagine it silently transforming sizeof(x) to sizeof(T), if you will.

#include 

int main()
{
    std::string a = "hello";
    std::string b = "Stack Overflow is for professional and enthusiast programmers, people who write code because they love it.";
    std::cout << sizeof(a) << std::endl;   // this prints 4 on my system
    std::cout << sizeof(b) << std::endl;   // this also prints 4 on my system
}

All C++ objects of the same type take up the exact amount of memory. Of course, since strings have vastly different lengths, they will internally store a pointer to a heap-allocated block of memory. But this does not concern sizeof. It couldn't, because as I said, sizeof operates at compile-time.