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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: sizeof environment variables array = 1?
Date: Thu, 08 Jun 2017 12:10:06 -0700
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DFS <nospam@dfs.com> writes:
> On 6/8/2017 12:43 PM, Lew Pitcher wrote:
>> but, I'd probably write it something like...
>> 
>>    int envars;
>> 
>>    /* advance through env[] array, looking for NULL pointer */
>>    for (envars = 0; env[envars] != NULL; ++envars) {/*NOP*/}
>> 
>>    printf("%d\n",envars);
>
>
> I just want to extract the Path env variable.



> This code hangs.  Am I misusing strncpy?
>
> int envars=0;
> char tmp[5];
> for (envars = 0; env[envars] != NULL; ++envars)
> {
> 	strncpy(tmp,env[envars],5);
> 	tmp[5]='\0';

Apart from the fact that you're assigning a value to the nonexisting
tmp[5] (which has already been covered), creating a copy of the initial
portion of the string is unnecessary.  Just use strncmp().

And be careful with strncpy(); it's not just a "safer" version of
strcpy().  (Usually the best way to be careful with it is to avoid using
it.)

> 	if (strcmp(tmp,"Path=")==0)
> 	{
> 		printf("%d. %s\n", envars+1, env[envars]);
> 		break;
> 	}		
> }

On Unix-like systems, there's an environment variable named "PATH", not
"Path".

I'm not sure about Windows.  As I recall it does use a similarly named
environment variable, but a lot of things in Windows are
case-insensitive.  I don't know whether you can rely on it being called
"Path" rather than, say, "path" or PATH".

And if your goal is to get the value of a particular environment
variable, I recommend the standard getenv() function.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"