String pattern matching program in CPP

CPP program for implement string pattern matching

#include<stdio.h>

#include<iostream.h>                                  

#include<conio.h>                   

#include<stdlib.h>

class string

{private:

          char s1[100],s2[100];

          int l1,l2,i;

public:

          void readstring();

          void displaystring();

          void compare();

};

void string:: readstring()

{        cout<<"\nEnter the first string  ";

gets(s1);

cout<<"\nEnter the second string  ";

gets(s2);

}

void string:: displaystring()

{        cout<<"\nThe first string  is \n " <<s1;

cout<<"\nThe second string  is \n " <<s2;

}

void string:: compare()

{

          l1=l2=0;

          for(i=0;s1[i]!='\0';i++)

                   l1++;

          for(i=0;s2[i]!='\0';i++)

                   l2++;

          if(l1>l2)

                   cout<<s1<<" is greater than "<<s2;

 else

                   if(l1<l2)

                   cout<<s1<<" is less than "<<s2;

          else

          {        int m=0,n=0;

                   cout<<"Strings are of same length\n";

                   for(i=0;i<l1;i++)

                   {        s1[i]=(s1[i] >='a'&&s1[i] <'z')?('A'+s1[i]-'a'):s1[i];

                             s2[i]=(s2[i] >='a'&&s2[i] <'z')?('A'+s2[i]-'a'):s2[i];

                             if(s1[i] <s2[i])

                                      m++;

                             else

                                      if(s1[i] >s2[i])

                             n++;

}

if(n==0&&m==0)

                   cout<<"\n and Strings are of same data\n";

else

                    cout<<"\n but, Strings are of not same data\n";

}

}

void main()

{        int c;

          char ch;

          string s;

          while(1)

          {        clrscr();

                   cout<<"Perform the following operations "<<endl;

                   cout<<"------------------------------------------"<<endl;

                   cout<<"1.Enter the strings \n";

                   cout<<"2.Display the strings \n";

                   cout<<"3.Compare the strings \n";

                    cout<<"4.Exit from Program \n";

                   do

                    {        cout<<"Select your choice(1:4)";

                              cin>>c;

                    }

                   while((c<1)||(c>4));

          if(c==4)exit(1);

          clrscr();

          switch(c)

          {case 1:

                             s.readstring();

break;

          case 2:

                   s.displaystring();

                   break;

          case 3:

                   s.compare();

                   break;

          }

          cout<<endl<<"Press any key to continue...";

          getch();

       }

}