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<title>15.5 Floating point support for standard ANSI functions</title>
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<a name="1205253"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">15.5 Floating point support for standard ANSI functions</font>
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<a name="1205254"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Floating point support is expensive in terms of code size. For this reason two versions of the library are provided, one which supports floating point and one which does not. By default the standard run-time libraries linked with a user application do not support floating point.</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1205255"> </a>If an attempt is made to format (using <font size=2 face=Courier><strong>sprintf</strong></font> or similar) a floating point number then the string "<font size=2 face=Courier><strong>[fp]</strong></font>" is written into the string instead of the number.</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1205256"> </a>If an attempt is made to read a floating point number (using <font size=2 face=Courier><strong>sscanf)</strong></font> then <font size=2 face=Courier><strong>sscanf</strong></font> stops conversion at that point and terminates immediately returning the number of inputs which have been successfully converted up to that point. No value is written into the associated float or double object.</font></p>
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<a name="1205257"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><em>Note: The functions <font size=2 face=Courier><strong>strtod</strong></font> and <font size=2 face=Courier><strong>atof</strong></font> return <font size=2 face=Courier><strong>0</strong></font> values if an attempt is made to use them when linking with the default libraries.</em></font>
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<a name="1205258"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">The full list of functions affected is:</font>
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<a name="1205260"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><font size=2 face=Courier><strong>atof<br>sprintf<br>vsprintf<br>sscanf<br>printf<br>strtod<br>snprintf </strong></font>(non-ANSI function)<br><font size=2 face=Courier><strong>vnsprintf</strong></font> (non-ANSI function)</font>
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<a name="1205267"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">To enable floating point support for these functions, use <strong>st20cc</strong> with the <font face="Verdana, Arial, Helvetica, sans-serif"><b>fp</b></font> option.</font>
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<a name="1205268"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">The degree of compliancy to the IEEE standard for floating point types is stated in <a href="impdet3.htm#1204501"><font color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>Section⌨️ 快捷键说明
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