write a program to show conversion from string to int and vice-versa.

#include<iostream.h>
#include<stdlib.h>
#include<string.h>
class string
{
private:
char str[ 20 ];
public:
string( )
{
str[ 0 ] = '\0';
}
string( char * s )
{
strcpy( str, s );
}
string( int a )
{
itoa( a, str, 10 );
}
operator int( )
{
int i = 0,l,ss = 0,k = 1;
l = strlen( str ) - 1;
while( l >= 0 )
{
ss = ss + ( str[ l ] - 48 ) * k;
l--;
k *= 10;
}
return ( ss );
}
void displaydata( )
{
cout << str;
}
};
void main( )
{
string s1 = 123;
cout << endl << "s1=";
s1.displaydata( );
s1 = 150;
cout << endl << "s1=";
s1.displaydata( );
string s2 ( "123" );
int i = int( s2 );
cout << endl << "i=" << i;
string s3 ( "456" );
i = s3;
cout << endl << "i=" << i;
}