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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>ecvt</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_003_187"> </a>NAME</h4><blockquote>ecvt, fcvt, gcvt - convert a floating-point number to a string</blockquote><h4><a name = "tag_000_003_188"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="stdlib.h.html">stdlib.h</a>>char *ecvt(double <i>value</i>, int <i>ndigit</i>, int *<i>decpt</i>, int *<i>sign</i>);char *fcvt(double <i>value</i>, int <i>ndigit</i>, int *<i>decpt</i>, int *<i>sign</i>);char *gcvt(double <i>value</i>, int <i>ndigit</i>, char *<i>buf</i>);</code></pre></blockquote><h4><a name = "tag_000_003_189"> </a>DESCRIPTION</h4><blockquote>The<i>ecvt()</i>,<i><a href="fcvt.html">fcvt()</a></i>and<i><a href="gcvt.html">gcvt()</a></i>functions convert floating-point numbers to null-terminated strings.<dl compact><dt><i>ecvt</i>()<dd>Converts<i>value</i>to a null-terminated string of<i>ndigit</i>digits (where<i>ndigit</i>is reduced to an unspecified limit determined by the precision of a<b>double</b>) and returns a pointer to the string. The high-order digit isnon-zero, unless the value is 0. The low-order digit is rounded. Theposition of the radix character relative to the beginning of the string isstored in the integer pointed to by<i>decpt</i>(negative means to the left of the returned digits).If<i>value</i>is zero, it is unspecified whether the integer pointed to by<i>decpt</i>would be 0 or 1.The radix character is not included in the returned string.If the sign of the result is negative, the integer pointed to by<i>sign</i>is non-zero, otherwise it is 0.If the converted value is out of range or is not representable,the contents of the returned string are unspecified.<dt><i>fcvt</i>()<dd>Identical to<i>ecvt()</i>except that<i>ndigit</i>specifies the number of digits desired after the radix point. The totalnumber of digits in the result string is restricted to an unspecified limit asdetermined by the precision of a <b>double</b>.<dt><i>gcvt</i>()<dd>Converts<i>value</i>to a null-terminated string (similar to that of the %g format of<i><a href="printf.html">printf()</a></i>)in the array pointed to by<i>buf</i>and returns<i>buf</i>.It produces<i>ndigit</i>significant digits (limited to an unspecified value determined by theprecision of a <b>double</b>) in %f if possible, or %e(scientific notation) otherwise. A minus sign is included in the returnedstring if <i>value</i> is less than 0. A radix character is included in thereturned string if <i>value</i> is not a whole number. Trailing zeros aresuppressed where <i>value</i> is not a whole number. The radix character isdetermined by the current locale.If<i><a href="setlocale.html">setlocale()</a></i>has not been called successfully, the default locale, "POSIX", is used. Thedefault locale specifies a period (<b>.</b>)as the radix character. The LC_NUMERIC category determines the value of theradix character within the current locale.</dl><p>These interfaces need not be reentrant.</blockquote><h4><a name = "tag_000_003_190"> </a>RETURN VALUE</h4><blockquote>The<i>ecvt()</i>and<i><a href="fcvt.html">fcvt()</a></i>functions return a pointer to a null-terminated string of digits.<p>The<i><a href="gcvt.html">gcvt()</a></i>function returns<i>buf</i>.<p>The return values from<i>ecvt()</i>and<i><a href="fcvt.html">fcvt()</a></i>may point to static data which may be overwritten by subsequent calls to thesefunctions.</blockquote><h4><a name = "tag_000_003_191"> </a>ERRORS</h4><blockquote>No errors are defined.</blockquote><h4><a name = "tag_000_003_192"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_003_193"> </a>APPLICATION USAGE</h4><blockquote>For portability to implementations conforming to earlier versions of thisspecification,<i><a href="sprintf.html">sprintf()</a></i>is preferred over this function.</blockquote><h4><a name = "tag_000_003_194"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_003_195"> </a>SEE ALSO</h4><blockquote><i><a href="printf.html">printf()</a></i>,<i><a href="setlocale.html">setlocale()</a></i>,<i><a href="stdlib.h.html"><stdlib.h></a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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