Sorting out duplicates between 2 char arrays [closed] - c++

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I'm struggling with an assignment for my class where we have to take input from the user into a char array (word) and take out the duplicates in the word inputted if needed. Comparing the array of the modified array (word) with the alphabet array (abc) to remove the repeated letters from the list. Once the duplicates are removed then just output the modified word followed by the new form of the alphabet into the newAbc array.
For example:
The word HELLO would first become HELO then after comparing to the alphabet the end output from the new array should be HELOABCDFGIJKMNPQRSTUVXYZ.
I'm stuck more on the for loops comparing the new word to the alphabet really.
char word[20], newAbc[40] = { '\0' };
char abc[27] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
int i = 0, b = 1, n = 0, leng, dup;
//dup counts up the repeats but is established in the first portion of the program but i've excluded it as it works perfectly.
cout << "Please enter a word: ";
cin >> word;
leng = strlen(word);
b = 0;
n = leng - dup;
i = 0;
for (i = 0; i < n; i++)
{
for (b = 0; b < 27; b++)
{
if (newAbc[i] != abc[b])
{
newAbc[n] = abc[b];
n++;
}
}
}
for (i = 0; i < 27; i++)
cout << newAbc[i];
cout << endl;
return 0;
}
I'd appreciate any kind of insight on my mistakes.

Answer 1

The major problem for crash is that you are changing n inside for loop for iterating in newAbc. And your if condition will be true for at least 25 times so incrementing n by 25(minimum) in each iteration resulting in accessing out of bound memory(SEG-FAULT).
for (i = 0; i < n; i++)
{
for (b = 0; b < 27; b++)
{
if (newAbc[i] != abc[b]) // this condition is not correct
{ // this will be true atleast 25 times
newAbc[n] = abc[b]; // wrong memory access
n++; // here is the problem
}
}
}
Assuming that your duplicate counting works fine, below are the changes required:-
char word[20];
// FIXME: your new array should not contain no duplicate so size can be 27
char newAbc[40] = {'\0'};
// FIXME: simply can be char abc[27] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char abc[27] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
cout << "Please enter a word: ";
cin >> word;
// dup counts up the repeats but is established in the first portion of
// the program but i've excluded it as it works perfectly.
// Lets say word = "HELLO"; so dup = 1, and newArray, should have "HELO"
memcpy(newAbc, "HELO", 4); // from your excluded part of code
int dup = 1; // from your excluded part of code
int leng = strlen(word); // length of input word
int n = leng - dup; // char remained to be inserted
// iterator for new array(newAbc)
int c = n; // n elements are already there
// Just reversed your loop
for (int b = 0; b < 27; b++)
{
int found = 0;
for (int i = 0; i < n; i++)
{
if (newAbc[i] == abc[b])
{
found = 1;
break;
}
}
if (!found)
{
newAbc[c] = abc[b];
c++;
}
}
for (int i = 0; i < 27; i++)
cout << newAbc[i];
cout << endl;
return 0;