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problem with while loop :(

chickens7 (19)
Hey guys;
This is my code for a project I was working on, the code is supposed to accept two strings from the user and determine if they are anagrams (by removing spaces and non characters/numbers from the strings). The code works correctly ... the first time, but when it loops to have the user enter two new words, it crashes. I cant for the life of me figure out why, any hints/tips would be much appreciated.

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 #include <iostream>
#include <string>
#include <cctype>

using namespace std;

class anagram
{
private:
	string input1, input2, mod1, mod2;
	string preprocess(string str);
	
public:
    
	anagram(string one, string two)
	{
		mod1=preprocess(one);
		mod2=preprocess(two);
	}
	
	bool isAnagram_iterative();
	
};

bool anagram::isAnagram_iterative()
{
	if(mod1.size() != mod2.size())
	{return false;}
	for (int i =0; i<mod1.size();i++)
	{
		if(mod1[i] ==mod2[i])
		{
			return true;
		}
		if(mod1[i] != mod2[i])
		{return false;}
	}
    return false;
    
}
string anagram::preprocess(string str)
{
	int num_nonletters=0;
    for (int i =0; i <str.size(); i ++)
    {
        if(str[i] == toupper(str[i]))
        {
            str[i] = tolower(str[i]);
        }
        
        if(ispunct(str[i]))
        {
            num_nonletters++;
        }
        if(isspace(str[i]))
        {
            num_nonletters++;
        }
    }
    
    char  temp;
	bool swap;
    
	do
	{	swap = false;
		for (int iterator = 0; iterator < (str.size() - 1); iterator++)
		{
			if (str[iterator] > str[iterator + 1])
			{
				temp = str[iterator];
				str[iterator] = str[iterator + 1];
				str[iterator + 1] = temp;
				swap = true;
			}
		}
    } while (swap);
	str=str.substr(num_nonletters);
    return str;
}

int main ()
{
	char ask;
	string first_word, word2;
	int iterator=1;
	do{
    cout << "input: " <<iterator <<endl;
    cout <<"Enter first input string: \n";
    getline(cin, first_word);
    cout <<"Enter second input string: \n";
    getline(cin, word2);
    anagram object(first_word,word2);
    if(object.isAnagram_iterative())
    {
        cout << "Iterative test passed!\n";
    }
    else 
    {	
        cout <<"Iterative test FAILED!\n";
    }
        cout << "run again \n";
        cin >> ask;
        iterator++;
    }while(ask=='y');
}
Chervil (7320)
The reason the error is triggered on the second pass of the loop, is the trailing newline '\n' remaining in the input buffer after cin >> ask; at line 102. That can be fixed by the use of cin.ignore().
102
103
 
            cin >> ask;
            cin.ignore(1000, '\n');


As for the actual error which causes the crash, it looks like your code cannot handle a zero-length string. That's something you should look at fixing either at the stage of getting user input, or in the anagram preprocess() function.
Last edited on
chickens7 (19)
that makes sense, I probably should have just used getline for the ask answer and turned it into a string variable; thank you for your quick response.
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