Cannot Loop Properly

[hentaiw]

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

using namespace std;


int main()
{
	char ans = 'y';
	string aString,fString;
	cout << "AntiSexist - By Kudy" << endl;
	do{
	cout << "Enter a line,I'll censor : ";
	getline(cin,aString);
	//My algorithm : Find the h,take 3 letter,check 2 whitespaces,correct
	int aLength = aString.length();
	for(int j=0;j<aLength;j++)
		aString[j]=tolower(aString[j]);
	if(aLength <= 3 && aLength >0)
	{
		cout << "Length <= 3,unable to convert -> may be grammatically incorrect !" << endl;
		for(int k=0;k<aLength;k++)
			fString += aString[k]; 
	};
	for(int i=0;i<aLength && aLength>3;i++)
		if((aString[i]=='h') && (aString[i+1]!='\n' && aString[i+2]!='\n'))
		{
			fString += "h";
			if(i==0)
			{
				string test = aString.substr(i,4);
				if((test[1]=='i'&&test[2]=='m')||(test[1]=='e'&&test[2]=='r'))
					if(test[3]==' ')
					{
						fString += "im or her";
						i+=2;
					}
			}else{
				string test = aString.substr(i-1,5);
				if((test[2]=='i'&&test[3]=='m')||(test[2]=='e'&&test[3]=='r'))
					if(test[0]==' ' && test[0]==' ')
					{
						fString += "im or her";
						i+=2;
					}
			};
		}else
			fString += aString[i]; 
	cout << fString << endl;
	cout << "Again (Y/N) ?";cin >> ans;
	}while(ans=='y'|| ans=='Y');
	return 0;
}

I cannot use do while to start a new session if user needs,maybe there's a endline but i don't know how to get it off

Subject if you need :

5.Write a program that can be used to train the user to use less sexist language by suggesting
alternative versions of sentences given by the user. The program will ask for a sentence,
read the sentence into a string variable, and replace all occurrences of masculine pro-
nouns with gender-neutral pronouns. For example, it will replace "he" by "she or he".
Thus, the input sentence
See an adviser, talk to him, and listen to him.
should produce the following suggested changed version of the sentence:
See an adviser, talk to her or him, and listen to her or him.
Be sure to preserve uppercase letters for the first word of the sentence. The pronoun "his"
can be replaced by "her(s)"; your program need not decide between "her" and "hers".
Allow the user to repeat this for more sentences until the user says she or he is done. This will
be a long program that requires a good deal of patience. Your program should not replace the
string "he" when it occurs inside another word such as "here". A word is any string consist-
ing of the letters of the alphabet and delimited at each end by a blank, the end of the line, or
any other character that is not a letter. Allow your sentences to be up to 100 characters long.

Plz help me...