#include <iostream>
using namespace std;


// C-string length, using array notation
int length(char* stringOfInterest)
{
     int length = 0;
     int i = 0;

     while (stringOfInterest[i] != NULL)
     {
          length = length + 1;
          i = i + 1;
     }
     return length;
}

// C-string length, using pointer notation
int length2(char* stringOfInterest)
{
     int length = 0;
     char* position;

     position = stringOfInterest;
     while (*position != '\0')
     {
          length = length + 1;
          position = position + 1;
     }
     return length;

}
// this implementation is similar to Jay's ideas from class
bool equal(char* stringOne, char* stringTwo)
{
     cout << "Running equality for " << stringOne << " and " << stringTwo << endl;
     int i,j;
     // NOTE THE TEST TO SEE IF WE GOT THE SAME POINTER (THAT'S AN AUTOMATIC TRUE FOR EQUAL)
     if (stringOne != stringTwo)
     {
          cout << "Checking characters: " << endl;
          i = 0;
          j = 0;
          while ((stringOne[i] != '\0') && (stringTwo[j] != '\0'))
          {
               // mismatch
               if (stringOne[i] != stringTwo[j]) return false;
               i = i + 1;
               j = j + 1;
          }
          // didn't get a mismatch character so test they are both on the null symbol
          if (stringOne[i] == '\0')
          {
               if (stringTwo[j] != '\0') return false;
          }
          else // already know stringOne is not on null symbol 
          {
               if (stringTwo[j] == '\0') return false;
          }
     }
     else
     {
          cout << "Pointer Match!" << endl;
     }
     return true; // if make it here, they are matched
}

// this implementation is similar to Charlie's ideas from class
bool equal2(char* stringOne, char* stringTwo)
{
     cout << "Running equality (test 2) for " << stringOne << " and " << stringTwo << endl;
     int i,j;
     if (stringOne != stringTwo)
     {
          cout << "Checking characters: " << endl;
          i = 0;
          j = 0;
          // while they match and we haven't hit the end... 
          while ((stringOne[i] == stringTwo[j]) && (stringOne[i] != '\0') && (stringTwo[j] != '\0'))
          {
               // keep moving up (we can reduce this even more (codewise) by using
               // pointer notation in the line above and the ++ that Charlie suggested in class
               i = i + 1;
               j = j + 1;
          }
          // at this point, know something has happened -- see what
          // their are four cases, but they minimize down to two
          // 1) you aren't the same string so two regular characters mismatched
          // 2) stringOne is shorter than the other, so the '\0' will mismatch against a real character
          // 3) stringTwo is shorter than the other, so same thing happens
          //  -- these are all caught here --
          if (stringOne[i] != stringTwo[i]) return false;
          // the other case is they are the same string, so just return true
          else return true;
     }
     else
     {
          cout << "Pointer Match!" << endl;
     }
     return true;
}


int main(int argc, char* argv[])
{
     int i;
     char* p = argv[1];
     cout << "Program Name: " << argv[0] << " length(): " << length(argv[0]) << " length2(): " << length2(argv[0]) << endl;
     for  (i = 1; i < argc; i++)
     {
          cout << "Argument " << i << ": " << argv[i] << " length(): " << length(argv[i]) << " length2(): " << length2(argv[i]) << endl;
     }

     if (equal(argv[1],argv[1])) 
          cout << "Match" << endl;
     else 
          cout << "Mismatch" << endl;

     if (equal(argv[1],p))
          cout << "Match" << endl;
     else
          cout << "Mismatch" << endl;
     
     if (equal(argv[1],argv[2]))
          cout << "Match" << endl;
     else 
          cout << "Mismatch" << endl;

     if (equal(argv[0],argv[2]))
          cout << "Match" << endl;
     else 
          cout << "Mismatch" << endl;


     if (equal2(argv[1],argv[1])) 
          cout << "Match" << endl;
     else 
          cout << "Mismatch" << endl;

     if (equal2(argv[1],p))
          cout << "Match" << endl;
     else
          cout << "Mismatch" << endl;
     
     if (equal2(argv[1],argv[2]))
          cout << "Match" << endl;
     else 
          cout << "Mismatch" << endl;

     if (equal2(argv[0],argv[2]))
          cout << "Match" << endl;
     else 
          cout << "Mismatch" << endl;
     return 0;
}