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String manipulation

HPexpress (18)
Working to compare two strings. I want to detect if there is a 1 character deletion between the strings and if not return false. My code is not properly detecting deletion errors and skips past this section.
3 type of 1 character deletions (1 char deleted at beginning, middle or end of word). I should account for all these situations but my code has trouble on the ends. 

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#include <iostream>
#include <string>

using namespace std;

int main()

{
bool comparison; 
int difference=0;
string word1, word2; 


cout << "Please enter two strings starting with string1." << endl; 
cin >> word1;
cin >> word2;

if (word1.length() != word2.length())
{
    for(int i=0; i < word1.length(); i++)
     {
       if (word1[i] != word2[i] && word1.substr[i+1] == word2.substr[i])
               comparison = true; 
       else
               comparison = false; 

     }

}
 
if (comparison)
cout << "true.";
else (!comparison)
cout << "false."; 


return 0; 
}


i have also tried doing something like the following but still come up with errors.. 
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int difference =0; 

if(word1.length() != word2.length())
{

    for (int i=0; i< word1.length(); i++)
      {
         if(word1[i] != word2[i])
            difference +=1;
      }
}

if (difference == 1)
cout << "true"; 
else
cout << "false";


Last edited on
TwoOfDiamonds (58)
I'm no expert but I'll try to help...
I think bool comparison; should be bool comparison = false; ... so the program will print "false" if the strings are the same ( obviously there was no deletion )
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if (comparison)
cout << "true.";
else (!comparison)
cout << "false."; 

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if (comparison)
cout << "true.";
else
cout << "false.";

and be sure that the original string is word1 and the string that suffered a deletion is word2 ... hope this helps a little
Last edited on
HPexpress (18)
Thank you for your assistance! However, I still keep getting error( 1 character deletion errors get sent to my outfile as "many errors" and not "deletion"). I'll post up my two functions and maybe someone else with a fresh eye can spot my logic error. I can post up the rest of the functions if someone wants to see it.Thank you again :D

bool function that detects error

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bool isDeletion (string correctWord, string userWord)
{
int difference =0;

if(correctWord.length()-1 == userWord.length())
{
    for(int i =0; i<correctWord.length();i++)
    {
        if(correctWord[i] != userWord[i])
        {
            difference +=1;

        }
    }
    if (difference == 1)
            return true;
        else
            return false;

}
else
    return false;
}



main function that calls bool for deletion error

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void testError(ifstream& fin, string correctWord, string userWord,spelling_error errorType, ofstream& fout)
{
int correct = 0;
int substitution =0;
int transposition =0;
int deletion = 0;
int insertion =0;
int error =0;
char ch;

fout << "*****Starting a new line*****" << endl;
fin  >> correctWord;
fout << "The correct word is " << correctWord << endl << endl;

while(!fin.eof())
{
  ch = ' ';

  while(ch != '\n')
  {
      fin >> userWord;
      fout << "The user word is " << userWord << endl;

if(correctWord.length() == userWord.length())
{
    if(correctWord == userWord)
      {
         errorType = CORRECT;
         printError(errorType,correct,substitution,transposition,deletion,insertion,error, fout);
      }
      else if (isSubstitution(correctWord, userWord))
      {
          errorType = SUBSTITUTION;
          printError(errorType,correct,substitution,transposition,deletion,insertion,error, fout);
      }
      else if (isTransposition(correctWord, userWord))
      {
          errorType = TRANSPOSITION;
          printError(errorType,correct,substitution,transposition,deletion,insertion,error, fout);
      }
}
else if(correctWord.length() != userWord.length())
{
      if (isDeletion(correctWord, userWord))
      {
          errorType = DELETION;
          printError(errorType,correct,substitution,transposition,deletion,insertion,error, fout);
      }
      else if(isInsertion(correctWord, userWord))
      {
          errorType = INSERTION;
          printError(errorType,correct,substitution,transposition,deletion,insertion,error, fout);
      }

      else
      {
          errorType = ERROR;
          printError(errorType,correct,substitution,transposition,deletion,insertion,error, fout);
      }
}
fin.get(ch);

  }

fout << "*****Starting a new line*****" << endl;
fin  >> correctWord;
fout << "The correct word is " << correctWord << endl << endl;

}

fout << "There were " << correct << " correct words." << endl;
fout << "There were " << substitution << " substitution errors." << endl;
fout << "There were " << transposition << " transposition errors." << endl;
fout << "There were " << deletion << " deletion errors." << endl;
fout << "There were " << insertion << " insertion errors." << endl;
fout << "There were " << error << " words with many mispellings." << endl;

}
Last edited on
TwoOfDiamonds (58)
in the bool function...
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bool isDeletion (string correctWord, string userWord)
{
int difference =0;

if(correctWord.length()-1 == userWord.length())
{
    for(int i =0; i<correctWord.length();i++)
    {
        if(correctWord[i] != userWord[i])
        {
            difference +=1;

        }
    }
    if (difference == 1)
            return true;
        else
            return false;

}
else
    return false;
}


since userWord is 1 char shorter than correctWord and you compare each char ... isn't it possible to compare the last char of correctWord with nothing ? thus creating an error ?
HPexpress (18)
sounds like that's my problem. I'm wondering how i can compare that last character if that is the deletion. I also tried comparing substrings after( i) is not equal but i still run into the problem with the last character if its a deletion. hmm

if (correctWord.length() -1 == userWord.length())

for (i =0; i<userWord.length(); i++)
return true;

I think that solved the problem. Another question lol so i have all my 1 error checks, but a few multiple error words throw it off. for instance two transposition errors in a word or an insertion or deletion. Any suggestions? an error counter for each function?
Last edited on
cire (8284)
If there's only one letter left to compare and difference is 0, it's a deletion.

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bool isDeletion (string correctWord, string userWord)
{
	if ( correctWord.length() == 0 )
		return false ;

	if (correctWord.length() == 1 && userWord.length() == 0 )
		return true ;

	if ( correctWord.length()-1 == userWord.length() )
	{
		unsigned cIdx = 0;
		unsigned uIdx = 0;

		while ( cIdx < correctWord.length() && uIdx < userWord.length() )
		{
			if ( correctWord[cIdx++] != userWord[uIdx++] )
			{
				if ( ++cIdx - uIdx > 1 ) // if this is the 2nd time we're doing this, return false
					return false ;
			}
		}

		return true ;
	}

	return false ;
}


I didn't think it was well suited for a for loop.
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