Convert Float To Char

Select Cast('100.1234' as float)
give me the result 100.1234
Now when I convert it back to char I want exactly 100.1234
Select Convert(char(100),Cast('100.1234' as float))
Gives me 100.123 (Here I was expecting 100.1234)

When I do
Select STR(Cast('100.1234' as float),25,4)
I get back the result as 100.1234

However here I am not sure how many digits do I have after the decimal
point. If I put some value like
Select STR(Cast('100.1234' as float),25,8)
I get 0's appended to it, which is again not desired.



Thanks in advance,
Jai