14. Write a C++ program that overloads the + operator and relational operators (suitable) to perform Concatenation of two strings and Comparison of two strings.

 Need for Class :
                Inorder to achieve the operator overloading.we must have to pass one object implicitly to overloading function.

Concatenation:
                default concatenation doesn't include space between arguments.
            Ex: Rama+Krishna=RamaKrishna      //but not "Rama Krishna"

Comparison:
                returns '0', if both the strings are "equal"
                returns '1' or +ve value, if the first string is greater than second
                returns '-1' or -ve value, if the second string is greater than first

#include<iostream.h>
class String
{
        private:
                char s[100];
        public:
                void input();
                void output();
                int operator<(String);
                void operator+(String);
};
int String::operator<(String a)
{
    int l1,l2,i;
    for(l1=0;s[l1]!='\0';++l1);         //length of first string
    for(l2=0;a.s[l2]!='\0';++l2);     //length of second string
    if(l1>l2)
    {   
        for(i=0;s[i]!='\0';++i)
        {
                if(a.s[i]!='\0'&&s[i]==a.s[i])
                        continue;
                else if(a.s[i]=='\0')     
                        return 1;
                return s[i]-a.s[i];
        }
        if(a.s[i]!='\0')
        return -1;
   }
   if(l1<=l2)
   {  
        for(i=0;a.s[i]!='\0';++i)
        {
                     if(s[i]!='\0'&&s[i]==a.s[i])
                        continue;
                else if(s[i]=='\0')
                        return -1;
                return s[i]-a.s[i];
        }
        if(a.s[i]!='\0')
        return 1;
   }
return 0;
}

void String::operator+(String a)
{
        int i,j;
        for( i=0;s[i]!='\0';++i);             //traversing first string upto the Null
        for( j=0;a.s[j]!='\0';++j,++i)     //Appending second string to first
        {
                s[i]=a.s[j];
        }
}

void String::input()
{
        cout<<"Please enter a string :"<<endl;
        cin>>s;
}

void String::output()
{
        cout<<"the string is :";
        cout<<s<<endl;
}
int main()
{
        String s1,s2;
        int c;
        cout<<"Reading first string .....";
        s1.input();
        cout<<"Reading second string .....";
        s2.input();
          c=s1<s2;
       if(c==0)
       cout<<"\nboth strings are equall";
       else if(c>0)
       cout<<"\nfirst string is larger than second";
       else
       cout<<"\nsecond string is larger than first";
       cout<<"\nAfter concatenation.......";
       s1+s2;
       s1.output();
       return 0;
}