Program:

//A sample program to test compare function of two strings
#include<iostream>
#include <string>
#include<cctype>
using namespace std;
bool compare(string s1,string s2);
//main function to test our compare function
int main()
{
	string s1,s2;
	cout<<"Enter two strings :"<<endl;
	getline(cin,s1);
	getline(cin,s2);
	bool res=compare(s1,s2);
	if(res)
		cout<<"Two strings are equal";
	else
		cout<<"Two strins are not equal";
	return 0;
}
//The function to compare two C-strings for equality
//ignore case, punctuation, and whitespace characters
bool compare(string s1,string s2)
{
	int length1,length2,max;
	length1=s1.length();
	length2=s2.length();
	if(length1>length2)
		max=length1;
	else
		max=length2;
	for(int i=0,j=0;i<max;i++,j++)
	{	
		//check upto last character whether character is punctuation 			
		//or white space in string1 and skip that character
		while((ispunct(s1[i]) || isspace(s1[i])) && i<max)
			i++;
		//check upto last character whether character is punctuation 			
		//or white space in string2 and skip that character
		while((ispunct(s2[j]) || isspace(s2[j])) && j<max)
			j++;
		//if i or j value is greater than max length of strings break 
		if(i==max || j==max)
			break;
		//convert both characters of both stribgs to lower and compare
		if(tolower(s1[i]) != tolower(s2[j]))
			return false;
	}
	return true;
}

TEST CASE 1 OUTPUT:

Enter two strings :
j''''''''''''
j
Two strings are equal

TEST CASE 2 OUTPUT:

Enter two strings :
jkkkj
jkk'j
Two strins are not equal

TEST CASE 3 OUTPUT:

Enter two strings :
as's''s 
asss
Two strings are equal