comparing values among them selves with in column

[genetist]

Hi,
i have data like this,
A B C
1 DD
2 DD
3 DD
4 CC
5 DD
6 DD
7 DD
8 DD
i want to compare data in B for example i want to compare A1 row i.e DD with A2 i.e DD if it is same then i want store that result in C as 1 , if it not match then C will be 0 like this i want to do for all rows in A with B and storing them in C. Is if condition will work for me? or i have to do something more? help needed in this,
Thanks in advance
I am expecting output like this,
A B C
1 DD 1
2 DD 1
3 DD 1
4 CC 0
5 DD 1
6 DD 1
7 DD 1
8 DD 1

 

[BengalMagic]

=if(countif(b:b,b1)>1,1,0)

 

[genetist]

=if(countif(b:b,b1)>1,1,0)

Thank you very much bengalMagic your formula is working perfectly and thanks lot