Convert char to float

[Dave Eisen]

In article <5051 at gara.une.oz.au> swijaya at gara.une.oz.au (Sastra Wijaya STMA) writes:
>I need to know how to convert a char variable into a float. The problem 

No you don't. You want to convert a time as stored in a struct tm into a
float. Let me say that (unless you are using a preexisting library
that expects dates in a floating point format) you probably shouldn't do
this. Floating point numbers are for things that really do have
floating decimal points (READ: Scientific computation) and should not
be used for things like money and dates that can be stored in a 
format more suited to their structure. I personally find a struct
tm to be a very convenient way of handling dates, we sometimes also use
a character string "YYMMDD.HHSS" or two ints -- yymmdd and hhss. I 
can't see what a float buys you.

>the variable tm is a struct of char.

No. It is a struct tm. It has nothing to do with characters.
>

>

>elapsed = (tm2.hour-tm.hour)*3600+(tm2.minute-tm.minute)*60+(tm2.second-tm.second) + (tm2.hsecond-tm.hsecond)/100;

You are using elapsed time in hundredths of seconds, this strikes as being
the same as working with money.

The best way to do this is to adopt a convention that time is measured
in hundredths of seconds. Then do

  int elapsed;

  elapsed = (tm2.hour - tm.hour) * 3600 * 100 + (tm2.minute - .....

If you ***really*** want to use floating point, your method seems as
good as any. 




--
Dave Eisen                      	    dkeisen at Gang-of-Four.Stanford.EDU
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