at school,I was given the class aName and asked to overload the input operator.the class has declared surname as type of char* and the surname is input from the keyboard and it must not be empty.please help me with the code.the class has declared the operator as its friend

post the class then we can discuss how to implement to >> operator.

class aName
{
friend std::istream operator>>(std::istream & input,aName &name);
/*input the name from the standard input stream like the keyboard and the name is never empty*/
friend std::ostream operator<<(std::ostream & output,aName name);
//it displays the name on the standard output like the screen

private:
char*surname,
       *firstname;

public:aName(char *aSurname,char*aFirstname);
void set(char *aSurname,char* afirstname)
{
if(aSurname=="")
  surname="";
else
surname=aSurname;
if(afirstname=="")
firstname="";
else
firstname=afirstname;
};

>>surname=aSurname;

First you have to allocate space for surname then call strcpy() to copy it

surname = new char[strlen(aSurname)+1];
strcpy(surname, aSurname);

The two friend functions must return a reference to the istream and ostream objects. Here's correction

#include <iostream>
#include <string>
#include <cstring>
using namespace std;
#pragma warning( disable: 4996) // only needed for VC++ 2008 compiler

class aName
{
friend std::istream& operator>>(std::istream & input,aName &name);
/*input the name from the standard input stream like the keyboard and the name is never empty*/
friend std::ostream& operator<<(std::ostream & output,aName name);
//it displays the name on the standard output like the screen

private:
char*surname,
    *firstname;

public:
    aName() { surname = NULL; firstname = NULL;}
    aName(char *aSurname,char*aFirstname)
    {
        surname = NULL; firstname = NULL;
        set(aSurname, aFirstname);
    }

    void set(char** name, const char* aName)
    {
        if( *name != NULL)
            delete[] *name;
        *name = NULL;
        if( aName != NULL)
        {
            *name = new char[strlen(aName)+1];
            strcpy(*name, aName);
        }
    }
    void set(const char *aSurname,const char* afirstname)
    {
        set(&surname, aSurname);
        set(&firstname, afirstname);
    }
};

istream& operator>>(istream& in, aName& nm)
{
    // TODO:  complete this function.
    return in;
}

int main()
{
    aName n;
    cin >> n;
}

[edit]Oops! I just noticed I did half your homework:(

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