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151 lines
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151 lines
7.0 KiB
HTML
4 years ago
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<title>strtol (The Red Hat newlib C Library)</title>
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<link href="Document-Index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<body lang="en">
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<a name="strtol"></a>
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<div class="header">
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<p>
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Next: <a href="strtoll.html#strtoll" accesskey="n" rel="next">strtoll</a>, Previous: <a href="strtod.html#strtod" accesskey="p" rel="prev">strtod</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="strtol_002c-strtol_005fl_002d_002d_002dstring-to-long"></a>
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<h3 class="section">2.38 <code>strtol</code>, <code>strtol_l</code>—string to long</h3>
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<a name="index-strtol"></a>
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<a name="index-strtol_005fl"></a>
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<a name="index-_005fstrtol_005fr"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <stdlib.h>
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long strtol(const char *restrict <var>s</var>, char **restrict <var>ptr</var>,
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int <var>base</var>);
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#include <stdlib.h>
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long strtol_l(const char *restrict <var>s</var>, char **restrict <var>ptr</var>,
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int <var>base</var>, locale_t <var>locale</var>);
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long _strtol_r(void *<var>reent</var>, const char *restrict <var>s</var>,
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char **restrict <var>ptr</var>,int <var>base</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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The function <code>strtol</code> converts the string <code>*<var>s</var></code> to
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a <code>long</code>. First, it breaks down the string into three parts:
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leading whitespace, which is ignored; a subject string consisting
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of characters resembling an integer in the radix specified by <var>base</var>;
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and a trailing portion consisting of zero or more unparseable characters,
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and always including the terminating null character. Then, it attempts
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to convert the subject string into a <code>long</code> and returns the
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result.
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</p>
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<p>If the value of <var>base</var> is 0, the subject string is expected to look
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like a normal C integer constant: an optional sign, a possible ‘<code>0x</code>’
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indicating a hexadecimal base, and a number. If <var>base</var> is between
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2 and 36, the expected form of the subject is a sequence of letters
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and digits representing an integer in the radix specified by <var>base</var>,
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with an optional plus or minus sign. The letters <code>a</code>–<code>z</code> (or,
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equivalently, <code>A</code>–<code>Z</code>) are used to signify values from 10 to 35;
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only letters whose ascribed values are less than <var>base</var> are
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permitted. If <var>base</var> is 16, a leading <code>0x</code> is permitted.
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</p>
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<p>The subject sequence is the longest initial sequence of the input
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string that has the expected form, starting with the first
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non-whitespace character. If the string is empty or consists entirely
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of whitespace, or if the first non-whitespace character is not a
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permissible letter or digit, the subject string is empty.
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</p>
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<p>If the subject string is acceptable, and the value of <var>base</var> is zero,
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<code>strtol</code> attempts to determine the radix from the input string. A
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string with a leading <code>0x</code> is treated as a hexadecimal value; a string with
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a leading 0 and no <code>x</code> is treated as octal; all other strings are
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treated as decimal. If <var>base</var> is between 2 and 36, it is used as the
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conversion radix, as described above. If the subject string begins with
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a minus sign, the value is negated. Finally, a pointer to the first
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character past the converted subject string is stored in <var>ptr</var>, if
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<var>ptr</var> is not <code>NULL</code>.
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</p>
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<p>If the subject string is empty (or not in acceptable form), no conversion
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is performed and the value of <var>s</var> is stored in <var>ptr</var> (if <var>ptr</var> is
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not <code>NULL</code>).
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</p>
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<p><code>strtol_l</code> is like <code>strtol</code> but performs the conversion based on the
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locale specified by the locale object locale. If <var>locale</var> is
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LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
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</p>
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<p>The alternate function <code>_strtol_r</code> is a reentrant version. The
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extra argument <var>reent</var> is a pointer to a reentrancy structure.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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<code>strtol</code>, <code>strtol_l</code> return the converted value, if any. If no
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conversion was made, 0 is returned.
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</p>
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<p><code>strtol</code>, <code>strtol_l</code> return <code>LONG_MAX</code> or <code>LONG_MIN</code> if the
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magnitude of the converted value is too large, and sets <code>errno</code>
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to <code>ERANGE</code>.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>strtol</code> is ANSI.
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<code>strtol_l</code> is a GNU extension.
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</p>
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<p>No supporting OS subroutines are required.
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</p>
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<br>
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<hr>
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<div class="header">
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<p>
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Next: <a href="strtoll.html#strtoll" accesskey="n" rel="next">strtoll</a>, Previous: <a href="strtod.html#strtod" accesskey="p" rel="prev">strtod</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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