fig19_09.cpp

经典vc教程的例子程序

// Fig. 19.9: fig19_09.cpp
// Converting to C-style strings.
#include <iostream>
#include <string>
using namespace std;

int main()
{
   string s( "STRINGS" );
   const char *ptr1 = 0;
   int len = s.length();
   char *ptr2 = new char[ len + 1 ]; // including null

   // Assign to pointer ptr1 the const char * returned by
   // function data(). NOTE: this is a potentially dangerous
   // assignment. If the string is modified, the pointer
   // ptr1 can become invalid.
   ptr1 = s.data();   
                      
   // copy characters out of string into allocated memory
   s.copy( ptr2, len, 0 );
   ptr2[ len ] = 0;  // add null terminator

   // output 
   cout << "string s is " << s 
        << "\ns converted to a C-Style string is "
        << s.c_str() << "\nptr1 is ";

   for ( int k = 0; k < len; ++k )
      cout << *( ptr1 + k );   // use pointer arithmetic

   cout << "\nptr2 is " << ptr2 << endl;
   delete [] ptr2;
   return 0;
}