Frustrated Pointer

// my first pointer
#include <iostream>
using namespace std;

int main ()
{
  int firstvalue, secondvalue;
  int * mypointer;

  mypointer = &firstvalue;
  *mypointer = 10;
  mypointer = &secondvalue;
  *mypointer = 20;
  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  return 0;
}

   

firstvalue is 10
secondvalue is 20

C Style of Substring

#include <string.h> /* for strncpy() */
#include <stdio.h> /* for printf() */

int
main(void)
{
char msg[] = "Hello World!";
char submsg[10]; /* Must be long enough */

/* Copy the substring "o W" from msg to submsg */
strncpy(submsg, &msg[4], 3);

/* Terminate the resulting string since strncpy() doesn't */
submsg[3] = '\0';

printf("msg[] = '%s'\nsubmsg[] = '%s'\n", msg, submsg);

return 0;
}