overloading >> operator

[Ashwin]

hi guys,

i have overloaded >operator for my own string class .the function is
as given below
istream& operator>>(istr eam &in,string1 &s)
{
char *a;
a=new char[100];
in>>a;
s=a;
return in;
}
i have also tried using a[100] and then using in>>a;
but in both the cases if i enter a string it gives segmentation fault.
and if i enter a character it works properly. if i give more than one
character it gives segmentation fault.what is the reason for this plzz
explain.
thanks in advance.

[Ian Collins]

Ashwin wrote:

>>>i am thinking of using char operator=(char ch);
and char operator[ ] (unsigned int i);
i don't know whether it will work or not have to try.

Doesn't make much sense.

hi Rolf,

i wanted to know how to overload the [] and = operator so that i can
implement the expression
s[1]='c'.

This isn't trivial, you have to differentiate between lvalue and rvalue
usage of operator[]. The normal technique is to return a proxy object
which supports assignment from char and conversion to char.

The best explanation I have seen of this in in Scott Meyers book "More
Effective C++"

--
Ian Collins.

[Rolf Magnus]

Ashwin wrote:

sorry Ian collins i wont use that abbrevation again . i have overloaded
both [ ] and = operator as follows
void operator=(char *s);

Should better be:

string1& operator=(const char* s);

void operator=(strin g1 s);

string1& operator=(const string1& s);

and
string1& operator+(char *s);

string1& operator+(const char *s);

char operator[](unsigned int i);

char operator[](unsigned int i) const;

where string1 is the string class i am writing.
so to implement the expression s[1]='c';
i donot know how to overload the operators

Try to add:

char& operator[](unsigned int i);

i am thinking of using char operator=(char ch);
and char operator[ ] (unsigned int i);
i don't know whether it will work or not have to try.

Doesn't make much sense.

hi Rolf,

i wanted to know how to overload the [] and = operator so that i can
implement the expression
s[1]='c'.

And I told you that you can't do it that way, but need to define a

char& operator[](unsigned int i);

instead.