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I've written the backbone for this code. I just needed a little insight on how i would complete the functions. i figure that a.swap(b) would work for swaping two strings within the same array. Am i wrong?

Any insight/ suggestions are appreciated.

#include <string>
using std::string;
#include <iostream>
#include <cassert>

using namespace std;

void swap(string & a, string & b); // swaps two strings.
void reverse_arr(string a1[], int n1); // reverse an array of strings.
void swap_arr(string a1[], int n1, string a2[], int n2); // swaps two arrays of strings.

int main(){
  string futurama[] = { “fry”, “bender”, “leela”, 
                        “professor farnsworth”, “amy”, 
                        “doctor zoidberg”, “hermes”, “zapp brannigan”, 
                        “kif”, “mom” };

  for (int i=0;i<10;i++)
    cout << futurama[i] << endl;

  swap(futurama[0],futurama[1]);
  cout << “After swap(futurama[0],futurama[1]);” << endl;

  for (int i=0;i<10;i++)
    cout << futurama[i] << endl;

  reverse_arr(futurama,10);
  cout << “After reverse_arr(futurama,10);” << endl;

  for (int i=0;i<10;i++)
    cout << futurama[i] << endl;

  // declare another array of strings and then 
  // swap_arr(string a1[], int n1, string a2[], int n2);

  char w;
  cout << “Enter q to exit.” << endl;
  cin >> w;
  return 0;
}

void swap(string & a, string & b){
  // swaps two strings.
  a.swap(b);
}

void reverse_arr(string a1[], int n1) {

// Reverse an array of strings.

}

void swap_arr(string a1[], int n1, string a2[], int n2) {

// swaps two arrays of strings.

}
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55% accept rate
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Indentation, please! – Carl Norum Mar 9 at 0:58
Check this out cplusplus.com/reference/string/swap – noMAD Mar 9 at 1:03
If "Am i wrong?" is your entire question, this will probably be closed. Are you having specific problems with this code? Is it working? If not, what specifically isn't doing what you'd expect? We're more than happy to help you with your homework, but you should at least ask meaningful questions. A vague "Am i wrong?" with nothing else isn't helpful (or an indication of trying to solve it yourself). – Ken White Mar 9 at 1:11
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1 Answer

up vote 0 down vote

The std::string::swap function will definitely swap two strings within an array ... it performs the exact same function as std::swap. That being said, since a std::string object actually is managing a dynamically allocated character string via pointers, the STL's versions of swap will not actually swap memory blocks. Therefore your function for swapping actual arrays will have to increment through the array and call swap for each element. For instance:

void swap_arr(string a1[], int n1, string a2[], int n2) 
{
    for (int i=0; i < min(n1, n2); i++)
    {
        swap(a1[i], a2[i]);
    }
}

For your reverse_arr function, you can do something very similar, but just make a pass through half the array (one slot less than the pivot position, which can either be an element, or between two elements), rather than the entire array, or else you're going to swap everything back into it's original position.

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Please don't provide code solutions to homework questions; it defeats the whole learning process. It's much better if you provide guidance to steer the asker in the right direction to solve the problem themselves (particularly in the case of questions that contain chunks of code and ask "Does this work?" or "Is this right?" with no indication that they've even tried the code first). It's much better for the person asking (and others in the future who may have to maintain code they write) if you help them to learn rather than provide copy/paste solutions. :) – Ken White Mar 9 at 1:15
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