data type of string literal

Hi List,

I just joined because I found a behaviour of implicit casts I don't
understand. I am quite new to Postgre, trying out things and
tried this sql-code:

select cast('8.000' as text) = 8.00 as test, 1 as case
union
select cast('8.000' as text) = 8.000, 2
union
select '8.00' = 8.000, 3

This gives me the following result:

test => f    case => 1
test => t    case => 2
test => t    case => 3

Why is the string literal in case 3 parsed as float so the
comparision is true. While in the other cases the
float literal is auto-casted to a string, so the
comparision is only true if the number of zeros is equal?

Is there a exact column type that fits a string literal? Explicit
casts to char or varchar instead of text gives the same results.

Yours,

Emil 'nobs' Obermayr