带字符串的动态内存分配

Question

My professor is currently teaching the topic of Dynamic Memory Allocation along with pointers. I don't quite understand the following example:

#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;

int main(void)
{
    int i;
    char * names[7];        // declare array of pointers to char
    char temp[16];

    // read in 7 names and dynamically allocate storage for each
    for (i = 0; i < 7; i++)
    {
        cout << "Enter a name => ";
        cin >> temp;
        names[i] = new char[strlen(temp) + 1];

        // copy the name to the newly allocated address
        strcpy(names[i],temp);
    }

    // print out the names
    for (i = 0; i < 7; i ++) cout << names[i] << endl;

    // return the allocated memory for each name
    for (i = 0; i < 7; i++) delete [] names[i];

    return 0;
}

For the line that prints out the names, I don't understand how "names[i]" prints out the names. Shouldn't "names[i]" print out the pointers instead? Any help on this is greatly appreciated.

Answer 1

There is an overload of operator<< with the following signature.

std::ostream& operator<<(std::ostream&, char const*);

which prints the null terminated string.

When you use

cout << names[i] << endl;

that overload is used.

You can see all the non-member overloads at http://en.cppreference.com/w/cpp/io/basic_ostream/operator_ltlt2 .

There is a member function overload of std::ostream with the signature:

std::ostream& operator<<( const void* value );

However, in the overload resolution logic, the non-member function with char const* as argument type is given higher priority.