hex string to float

[mastergriller]

I'm new to Tcl and need some help. I have a string that represents a float - example: bc4229d3 = -0.011850791. I can convert it to an integer but not to a float. In C I can cast it but I can't find a way to do that in Tcl. I know I can call a C routine but I would prefer to do it in Tcl only if possible. I tried everything I could find in the books I have available to me. As a final thought I tried converting it to an integer and or'ing it into a float but got an error on that.

% set x 0.0
0.0
% set y [expr $x | 0xbc42249d3]
can't use floating-point value as operand of "|"

I'm out of ideas, can anyone help?

-mastergriller

 

[mastergriller]

I found the answer to this problem.

set hex "d32942bc"
set bin [binary format H8 $hex]
binary scan $bin f* float
puts "$float"

Being so new to Tcl I don't know if there's a "gotsha" in this but it seems to work. If anyone has more information of when this won't work please let me know.

-mastergriller