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<a name="Floating_002dPoint-Conversions"></a>
<div class="header">
<p>
Next: <a href="Other-Output-Conversions.html#Other-Output-Conversions" accesskey="n" rel="next">Other Output Conversions</a>, Previous: <a href="Integer-Conversions.html#Integer-Conversions" accesskey="p" rel="prev">Integer Conversions</a>, Up: <a href="C_002dStyle-I_002fO-Functions.html#C_002dStyle-I_002fO-Functions" accesskey="u" rel="up">C-Style I/O Functions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Floating_002dPoint-Conversions-1"></a>
<h4 class="subsection">14.2.9 Floating-Point Conversions</h4>
<p>This section discusses the conversion specifications for floating-point
numbers: the ‘<samp>%f</samp>’, ‘<samp>%e</samp>’, ‘<samp>%E</samp>’, ‘<samp>%g</samp>’, and ‘<samp>%G</samp>’
conversions.
</p>
<p>The ‘<samp>%f</samp>’ conversion prints its argument in fixed-point notation,
producing output of the form
[<code><span class="nolinebreak">-</span></code>]<var>ddd</var><code>.</code><var>ddd</var><!-- /@w -->,
where the number of digits following the decimal point is controlled
by the precision you specify.
</p>
<p>The ‘<samp>%e</samp>’ conversion prints its argument in exponential notation,
producing output of the form
[<code><span class="nolinebreak">-</span></code>]<var>d</var><code>.</code><var>ddd</var><code>e</code>[<code>+</code>|<code><span class="nolinebreak">-</span></code>]<var>dd</var><!-- /@w -->.
Again, the number of digits following the decimal point is controlled by
the precision. The exponent always contains at least two digits. The
‘<samp>%E</samp>’ conversion is similar but the exponent is marked with the letter
‘<samp>E</samp>’ instead of ‘<samp>e</samp>’.
</p>
<p>The ‘<samp>%g</samp>’ and ‘<samp>%G</samp>’ conversions print the argument in the style
of ‘<samp>%e</samp>’ or ‘<samp>%E</samp>’ (respectively) if the exponent would be less
than -4 or greater than or equal to the precision; otherwise they use the
‘<samp>%f</samp>’ style. Trailing zeros are removed from the fractional portion
of the result and a decimal-point character appears only if it is
followed by a digit.
</p>
<p>The following flags can be used to modify the behavior:
</p>
<dl compact="compact">
<dt>‘<samp>-</samp>’</dt>
<dd><p>Left-justify the result in the field. Normally the result is
right-justified.
</p>
</dd>
<dt>‘<samp>+</samp>’</dt>
<dd><p>Always include a plus or minus sign in the result.
</p>
</dd>
<dt>‘<samp> </samp>’</dt>
<dd><p>If the result doesn’t start with a plus or minus sign, prefix it with a
space instead. Since the ‘<samp>+</samp>’ flag ensures that the result includes
a sign, this flag is ignored if you supply both of them.
</p>
</dd>
<dt>‘<samp>#</samp>’</dt>
<dd><p>Specifies that the result should always include a decimal point, even
if no digits follow it. For the ‘<samp>%g</samp>’ and ‘<samp>%G</samp>’ conversions,
this also forces trailing zeros after the decimal point to be left
in place where they would otherwise be removed.
</p>
</dd>
<dt>‘<samp>0</samp>’</dt>
<dd><p>Pad the field with zeros instead of spaces; the zeros are placed
after any sign. This flag is ignored if the ‘<samp>-</samp>’ flag is also
specified.
</p></dd>
</dl>
<p>The precision specifies how many digits follow the decimal-point
character for the ‘<samp>%f</samp>’, ‘<samp>%e</samp>’, and ‘<samp>%E</samp>’ conversions. For
these conversions, the default precision is <code>6</code>. If the precision
is explicitly <code>0</code>, this suppresses the decimal point character
entirely. For the ‘<samp>%g</samp>’ and ‘<samp>%G</samp>’ conversions, the precision
specifies how many significant digits to print. Significant digits are
the first digit before the decimal point, and all the digits after it.
If the precision is <code>0</code> or not specified for ‘<samp>%g</samp>’ or
‘<samp>%G</samp>’, it is treated like a value of <code>1</code>. If the value being
printed cannot be expressed precisely in the specified number of digits,
the value is rounded to the nearest number that fits.
</p>
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<p>
Next: <a href="Other-Output-Conversions.html#Other-Output-Conversions" accesskey="n" rel="next">Other Output Conversions</a>, Previous: <a href="Integer-Conversions.html#Integer-Conversions" accesskey="p" rel="prev">Integer Conversions</a>, Up: <a href="C_002dStyle-I_002fO-Functions.html#C_002dStyle-I_002fO-Functions" accesskey="u" rel="up">C-Style I/O Functions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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