Hello, I have run across a problem where I am losing some precision when writing numbers to a file, and then re-reading them for future use. I have captured an example of my problem in the following script: 

#sample data set
$Day = 0;
$Seconds = 35247;
$MicroSeconds = 755605;


#combine times into one variable
$Time = $Day + ($Seconds+$MicroSeconds/1000000)/86400;

#write this time to a file
open(FILE,"> test.txt");
printf FILE ("%1.20f",$Time);
close(FILE);


#read that time back in from file
open(FILE,"< test.txt");
@FileContents = <FILE>;
$FileTime = $FileContents[0];

#calculate diffence from time stored in memory and written to file
$Difference = $Time - $FileTime;

#print results
print "\nFrom Memory: ";
printf("%1.20f",$Time);
print "\nFromFile   : ";
printf("%1.20f",$FileTime);
print "\nDifference : ";
printf("%1.20f",$Difference);

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When I ran this on my Windows XP machine, it produced the output: 
From Memory: 0.40796013431712963000
FromFile   : 0.40796013431712957000
Difference : 0.00000000000000005551

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However, when I looked in the "test.txt" file, the number 0.40796013431712963000 was sitting in there. Why is this different from the "FromFile" number? Is there a way to make sure that the number is read exactly as it is from the file? Thanks for the help.

In reply to losing precision reading numbers from file by iKnowNothing

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