📄 getopt.html

📁 unix 下的C开发手册,还用详细的例程。
💻 HTML
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>getopt</title></head><body bgcolor=white><center><font size=2>The Single UNIX &reg; Specification, Version 2<br>Copyright &copy; 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_005_617">&nbsp;</a>NAME</h4><blockquote>getopt, optarg, optind, opterr, optopt - command option parsing</blockquote><h4><a name = "tag_000_005_618">&nbsp;</a>SYNOPSIS</h4><blockquote><pre><code>#include &lt;<a href="unistd.h.html">unistd.h</a>&gt;int getopt(int <i>argc</i>, char * const <i>argv</i>[], const char *<i>optstring</i>);extern char *optarg;extern int optind, opterr, optopt;</code></pre></blockquote><h4><a name = "tag_000_005_619">&nbsp;</a>DESCRIPTION</h4><blockquote>The<i>getopt()</i>function is a command-line parserthat can be used by applications that followUtility Syntax Guidelines 3, 4, 5, 6, 7, 9 and 10 in the <b>XBD</b> specification, <a href="../xbd/utilconv.html#usg"><b>Utility Syntax Guidelines</b>&nbsp;</a>.The remaining guidelines are not addressed by<i>getopt()</i>and are the responsibility of the application.<p>The parameters<i>argc</i>and<i>argv</i>are the argument count and argument array as passed to<i>main()</i>(see<i>exec</i>).The argument<i>optstring</i>is a string of recognised option characters; if a character is followed by acolon, the option takes an argument.  All option characters allowed by UtilitySyntax Guideline 3 are allowed in<i>optstring</i>.The implementation may accept other characters as an extension.<p>The variable<i>optind</i>is the index of the next element of the<i>argv</i>[]vector to be processed.It is initialised to 1 by the system, and<i>getopt()</i>updates it when it finishes with each element of<i>argv</i>[].When an element of<i>argv</i>[]contains multiple option characters,it is unspecified how<i>getopt()</i>determines which options have already been processed.<p>The<i>getopt()</i>function returns the next option character (if one is found) from<i>argv</i>that matches a character in<i>optstring</i>,if there is one that matches.If the option takes an argument,<i>getopt()</i>sets the variable<i>optarg</i>to point to the option-argument as follows:<ol><p><li>If the option was the last character in the stringpointed to by an element of<i>argv</i>,then<i>optarg</i>contains the next element of<i>argv</i>,and<i>optind</i>is incremented by 2.If the resulting value of<i>optind</i>is not less than<i>argc</i>,this indicates a missing option-argument, and<i>getopt()</i>returns an error indication.<p><li>Otherwise,<i>optarg</i>points to the string following the option characterin that element of<i>argv</i>,and<i>optind</i>is incremented by 1.<p></ol><p>If, when<i>getopt()</i>is called:<pre><code> <i>argv</i>[optind]    is a null pointer*<i>argv</i>[optind]    is not the character - <i>argv</i>[optind]    points to the string "-"</code></pre><i>getopt</i>()returns -1 without changing<i>optind</i>.If:<pre><code><i>argv</i>[optind]     points to the string "--"</code></pre><i>getopt</i>()returns -1 after incrementing<i>optind</i>.<p>If<i>getopt()</i>encounters an option character that is not contained in<i>optstring</i>,it returns the question-mark (?) character.If it detects a missing option-argument, it returns the colon character (:)if the first character of<i>optstring</i>was a colon, or a question-mark character (?) otherwise.In either case,<i>getopt()</i>will set the variable<i>optopt</i>to the option character that caused the error.If the application has not set the variable<i>opterr</i>to 0 and the first character of<i>optstring</i>is not a colon,<i>getopt()</i>also prints a diagnostic message to<i>stderr</i>in the formatspecified for the<i><a href="../xcu/getopts.html">getopts</a></i>utility.<br></blockquote><h4><a name = "tag_000_005_620">&nbsp;</a>RETURN VALUE</h4><blockquote>The<i>getopt()</i>function returns the next option character specified on the command line.<p>A colon (:) is returned if<i>getopt()</i>detects a missing argument and the first character of<i>optstring</i>was a colon (:).<p>A question mark (?) is returned if<i>getopt()</i>encounters an option character not in<i>optstring</i>or detects a missing argument and the first character of<i>optstring</i>was not a colon (:).<p>Otherwise<i>getopt()</i>returns -1 when all command line options are parsed.</blockquote><h4><a name = "tag_000_005_621">&nbsp;</a>ERRORS</h4><blockquote>No errors are defined.</blockquote><h4><a name = "tag_000_005_622">&nbsp;</a>EXAMPLES</h4><blockquote>The following code fragment shows how one might process the arguments for autility that can take the mutually exclusive options a and b andthe options f and o, both of which require arguments:<pre><code>#include &lt;unistd.h&gt;intmain (int argc, char *argv[ ]){    int c;    int bflg, aflg, errflg;    char *ifile;    char *ofile;    extern char *optarg;    extern int optind, optopt;    . . .    while ((c = getopt(argc, argv, ":abf:o:")) != -1) {        switch (c) {        case 'a':            if (bflg)                errflg++;            else                aflg++;            break;        case 'b':            if (aflg)                errflg++;            else {                bflg++;                bproc();            }            break;        case 'f':            ifile = optarg;            break;        case 'o':            ofile = optarg;            break;            case ':':       /* -f or -o without operand */                    fprintf(stderr,                            "Option -%c requires an operand\n", optopt);                    errflg++;                    break;        case '?':                    fprintf(stderr,                            "Unrecognised option: -%c\n", optopt);            errflg++;        }    }    if (errflg) {        fprintf(stderr, "usage: . . . ");        exit(2);    }    for ( ; optind &lt; argc; optind++) {        if (access(argv[optind], R_OK)) {    . . .}</code></pre>This code accepts any of the following as equivalent:<pre><code>cmd -ao arg path pathcmd -a -o arg path pathcmd -o arg -a path pathcmd -a -o arg -- path pathcmd -a -oarg path pathcmd -aoarg path path</code></pre></blockquote><h4><a name = "tag_000_005_623">&nbsp;</a>APPLICATION USAGE</h4><blockquote>The<i>getopt()</i>function is only required to support option characters included in Guideline 3.Many historical implementations of<i>getopt()</i>support other characters as options.This is an allowed extension, but applications that use extensions arenot maximally portable.Note that support for multi-byte option characters isonly possible when such characters can be represented as type<b>int</b>.<p>The<i>getopt()</i>interface need not be reentrant.</blockquote><h4><a name = "tag_000_005_624">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_625">&nbsp;</a>SEE ALSO</h4><blockquote><i><a href="exec.html">exec</a></i>,<i><a href="../xcu/getopts.html">getopts</a></i>,<i><a href="unistd.h.html">&lt;unistd.h&gt;</a></i>,the <b>XCU</b> specification.</blockquote><h4>DERIVATION</h4><blockquote>Derived from Issue 1 of the SVID.</blockquote><hr size=2 noshade><center><font size=2>UNIX &reg; is a registered Trademark of The Open Group.<br>Copyright &copy; 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

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -