#parsing options from stdin

19 messages · Page 1 of 1 (latest)

magic vine
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Im creating a program that shows a prompt and then based on the input does something
the input is something like (option) Ni [Nj Nk ...] eg insert Ni Nj each option can be an entire string, eg insert,find,modify or can have a shorthand i,f,m (the previous example is equivelant to i Ni Nj) (shorthands are 1-2 charachters long)

Is there any smart way to parse this input? I feel like a bunch of else ifs with strcmp isnt the answer...

winter iglooBOT
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frigid lantern
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I wouldn't say it is super bad, bunch of strcmp, another possibility is to make a struct and build a table to scan with elements like {"insert", 'i', function_handling_insert}

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then there's a question if you feel a need to do faster string search, then you may e.g. consider using glib as it has hash tables, so no need to reinvent the wheel

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well, I mean if all would be unique on first character then it is not much of a job for searching

magic vine
magic vine
magic vine
frigid lantern
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[
  {"insert", 'i', function_handling_insert},
  {"remove", 'r', function_handling_remove}
]
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you can just iterate over it

magic vine
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yeah I get it, this should make the code more readable, but still seems off

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I feel like there should be something better, maybe im wrong

frigid lantern
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I mean besides going into more elaborate data structures to find elements faster I don't think there is

magic vine
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what about parsing command line arguments? eg -i inputfile and -o outfile and more options which could be in random order when executing the program? eg $ ./foo -i bar -o baz

winter iglooBOT
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man7
getopt(3)

getopt, getopt_long, getopt_long_only, optarg, optind, opterr, optopt - Parse command-line options

Synopsis
#include <unistd.h>

int getopt(int argc, char *const argv[],
           const char *optstring);

extern char *optarg;
extern int optind, opterr, optopt;

#include <getopt.h>

int getopt_long(int argc, char *const argv[],
           const char *optstring,
           const struct option *longopts, int *longindex);
int getopt_long_only(int argc, char *const argv[],

... (truncated)

frigid lantern
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that's my go to

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both because I like the convention used and to not reinvent the wheel

marble grail