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String-to-Number Conversion Precision

• To: mathgroup at smc.vnet.net
• Subject: [mg112352] String-to-Number Conversion Precision
• From: Ben <benp84 at gmail.com>
• Date: Fri, 10 Sep 2010 04:50:06 -0400 (EDT)

I'm reading real numbers from a file and I'm trying to convert them
from string format (with arbitrary precision) to real values with the
same precision as given in the strings.

For example, when I convert "1.867524468", I want the result to be set
to precision 10.  Instead, I get the following.

In[1]:=    string = "1.867524468"
Out[1]:= "1.867524468"

In[2]:=    x = ToExpression[string]
Out[2]:= 1.86752

The last 4-digits get cut off.  This is fine for when I do math with
the number because the extra digits are still stored, but not when I
want to rewrite the number to a different file.  When I convert the
number back to a string for file output, the last 4-digits remain
lost.

In[3]:=    ToString[x]
Out[3]:= "1.86752"

Is there a function or formula I can use to automatically set the
precision of these numbers to their precision in the string?  Thanks.