data type of string literal

[nobs(at)nobswolf(dot)info (Emil Obermayr)]

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