Topical Information

This lab will give you more practice with the String class we developed in lecture (as well as with operator overloading).

Program Information

Develop a substring operator using operator(). The arguments should be the starting position for the substring and the length of the substring. The result should be a copy of the substring starting at the given position within our own data and ending at most the given length from the start. For example: 

    Object's Value     Operator Call       Resulting Object's Value
     "bob wuz here"        obj(0,4)         "bob "
     "bob wuz here"        obj(8,14)        "here"       (ran out of characters)
     "bob wuz here"        obj(14,4)        ""           (nothing there)
     "bob wuz here"        obj(4,1)         "w"

If the start position doesn't exist, send back an empty string (as we've defined). If there aren't 'length' characters left in our string after the given start position, return what we do have.

Don't forget to write a test application to show that your operator works. (Perhaps you could modify the existing String test app?)

Thought Provoking Questions

  1. Should this operator be a member or a non-member?

  2. Should it be applicable to constant Strings? (Does your operator change the original String object?)

  3. Where might such an operator come in handy? (Maybe on a previous lab?)

This assignment is (Level 2).

Options

Add (Level 1.5) to allow for negative lengths. I'll leave it up to you to decide if the resulting String should be forwards: 

    Object's Value     Operator Call       Resulting Object's Value
     "bob wuz here"        obj(0,-4)        ""           (nothing there)
     "bob wuz here"        obj(8,-14)       "bob wuz h"  (ran out of characters)
     "bob wuz here"        obj(14,-4)       "e"
     "bob wuz here"        obj(4,-1)        "w"
     "bob wuz here"        obj(4,-2)        " w"

Or backwards: 

    Object's Value     Operator Call       Resulting Object's Value
     "bob wuz here"        obj(0,-4)        ""           (nothing there)
     "bob wuz here"        obj(8,-14)       "h zuw bob"  (ran out of characters)
     "bob wuz here"        obj(14,-4)       "e"
     "bob wuz here"        obj(4,-1)        "w"
     "bob wuz here"        obj(4,-2)        "w "

Add (Level 1) to overload the ~ operator to return the reversed elements of a String: 

    Object's Value     Operator Call       Resulting Object's Value
     "bob"                ~obj                  "bob"
     "wuz"                ~obj                  "zuw"

Make sure to test this operator, too.

More Thought Provoking Questions