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POC/C++ getopt optstring syntax
 

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    <p>Using the <code>getopt</code> function included in unistd.h in C++, is there a way to structure the optstring such that...</p> <p><code>[-a] [-f "reg_expr"] out_file1 [[-f "reg_expr"] out_file2 ...]</code> is possible?</p> <p>This is a homework assignment, but the emphasis is not on this specific subtask.</p> <p>In my head I would like to specify the following logic:</p> <p>(a argument), (infinitely many f arguments with 2 required (sub)arguments),... (infinitely many generic arguments)</p> <p>Perhaps my understanding of the <code>getopt</code> function is fundamentally flawed. I also saw a <code>getopt_long</code>. Perhaps that is what I'm missing.</p> <p>I originally drafted this, which worked, but I came across the <code>getopt</code> function and thought it might do a better job.</p> <pre><code>int outFileFlags; int outFileMode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; int i = 1; while (i &lt; argc){ if (i == 1 &amp;&amp; strcmp( argv[i], "-a") == 0){ cout &lt;&lt; "append flag set" &lt;&lt; endl; outFileFlags = O_RDWR | O_APPEND; i++; continue; } else { outFileFlags = O_TRUNC | O_RDWR | O_CREAT; } if (strcmp( argv[i], "-f") == 0 &amp;&amp; i+2 &lt;= argc){ cout &lt;&lt; " regx = " &lt;&lt; argv[i+1] &lt;&lt; endl; cout &lt;&lt; " fn = " &lt;&lt; argv[i+2] &lt;&lt; endl; i = i+3; continue; } else { cout &lt;&lt; " regx = none" &lt;&lt; endl; cout &lt;&lt; " fn = " &lt;&lt; argv[i] &lt;&lt; endl; i++; continue; } } </code></pre> <p>Note: assume this is written for a unix environment. I don't think I can use anything from the standard library. I only included std::cout for testing purposes.</p> <p>I will be happy to elaborate on any details of the assignment. However, the main question revolves around the syntax of the optstring. I am currently only aware of : meaning required and :: meaning optional is there a way to specify arguments that repeat like a regex wildcard *?</p> <p>EDIT:</p> <p>I'm sure this is sloppy due to the fact that I don't think getopt is designed to handle multiple arguments per option but it does the trick...</p> <pre><code>int main(int argc, char *argv[]){ char c; int iterations = 0; while (*argv) { optind = 1; if (iterations == 0){ opterr = 0; c = getopt(argc, argv, "a"); if(c == 'a'){ //~ APPEND SET } else if(c=='?'){ optind--; } } while ((c = getopt(argc, argv, "f:")) != -1) { if (c == 'f'){ //~ REGEX = optarg if (optind &lt; argc &amp;&amp; strcmp(argv[optind], "-f") != 0) { //~ FILENAME = argv[optind] optind++; } else { errno = 22; perror("Error"); exit(errno); } } else { errno = 22; perror("Error"); exit(errno); } } argc -= optind; argv += optind; iterations++; //~ REMAINING FILES = *argv } } </code></pre>
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