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From: Phil Ashby <phil.eternal@ashbysoft.com>
Newsgroups: comp.lang.c
Subject: Re: is it possible to point to a slice of an array without malloc or
 VLAs?
Date: Wed, 28 Aug 2024 09:13:39 +0100
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On 28/08/2024 08:06, Mark Summerfield wrote:
> I'm using getopt_long() to process a command line. So after a typical
> call I might have:
> 
> argv == {"./efind", "-D", "-x", "one", "two", "three", "four"} optind
> == 3
> 
> What I'd like to do (without copying or mallocing and without using a
> VLA) is to get a pointer to a slice of argv, specifically, {"one",
> "two", "three", "four"}. In Python terms argv[optind:argc].
> 
> Is this possible in C?

To answer the specific question, I would use pointer arithmetic,
provided there is no intention to modify values, ie:

	char **slice = argv + config->optind;

thus slice now points at the appropriate part of argv and can be indexed
or dereferenced / incremented to access elements.

> At the moment I store argv, optind, and argc and handle the slice
 > using a loop:
> 
> if (config->optind < config->argc) for (int i = config->optind; i <
> config.argc; ++i) process(config->argv[i]);
> 
> This works fine, so really I'm just wondering if there's a nicer
> way.
I don't think so, other than to drop the outer check as the loop
condition provides the same boundary.

Phil.