I’ve two programs, one written in C, and onother one written in C++.
After some time I’ve noticed that the getopt function that gets
linked in a C program differs from the one linked within the C++ one.
The getopt in c supports the “-oVALUE” style. The SAME program linked
with QCC or qcc -lang-c++ will return an error when a parameter like
this is found.
Both funtions NEVER returns the ‘:’ when a parameter is missing.
Has someone experienced these problems?
–
Wave++
Wave++ <wavexx@apexmail.com> wrote:
I’ve two programs, one written in C, and onother one written in C++.
After some time I’ve noticed that the getopt function that gets
linked in a C program differs from the one linked within the C++ one.The getopt in c supports the “-oVALUE” style. The SAME program linked
with QCC or qcc -lang-c++ will return an error when a parameter like
this is found.Both funtions NEVER returns the ‘:’ when a parameter is missing.
Has someone experienced these problems?
Can you post an example, along with compile and link parameters?
Colin Burgess <cburgess@qnx.com> wrote:
Can you post an example, along with compile and link parameters?
after trying to replicate the problem I’ve noticed that the real
problem is more subtle:
getopt.c – begin
#include <unistd.h>
#include <stdio.h>
int main(int argc, char* argv[])
{
int brk = 1, c = 0;
opterr = 0;
while(brk && ( c = getopt( argc, argv, “ab”)) != -1)
switch( c )
{
case ‘a’: printf(“a\n”);
break;
case ‘b’: printf(“b\n”);
break;
case ‘:’: printf(“will never reach this\n”);
break;
case ‘?’: printf(“unsupported option\n”);
brk = 0;
break;
}
opterr = optind = 1;
while(( c = getopt( argc, argv, “abc:”)) != -1)
switch( c )
{
case ‘a’: printf(“a2\n”);
break;
case ‘b’: printf(“b2\n”);
break;
case ‘c’: printf(“c2 == %s\n”, optarg);
break;
case ‘:’: printf(“will never reach this (2)\n”);
break;
}
return 0;
}
getopt.c --end
I compile it using qcc -o getopt getopt.c
and ran this as follows:
$ ./getopt -c
unsupported option
getopt: option requires an argument – c
$ ./getopt -c 2
unsupported option
c2 == 2
$ ./getopt -c2
unsupported option
getopt: illegal option – 2
$
getopt here seems to use another internal static data that
doesn’t get reset on the next function call.
this data resets only when getopt terminates with -1.
You will notice however that ‘:’ never gets returned even
when setting opterr to 0 or ‘:’ as documented.
–
Wave++
Wave++ <wavexx@apexmail.com> wrote:
Colin Burgess <> cburgess@qnx.com> > wrote:
Can you post an example, along with compile and link parameters?after trying to replicate the problem I’ve noticed that the real
problem is more subtle:getopt.c – begin
#include <unistd.h
#include <stdio.hint main(int argc, char* argv[])
{
int brk = 1, c = 0;opterr = 0;
while(brk && ( c = getopt( argc, argv, “ab”)) != -1)
switch( c )
{
case ‘a’: printf(“a\n”);
break;
case ‘b’: printf(“b\n”);
break;
case ‘:’: printf(“will never reach this\n”);
break;
case ‘?’: printf(“unsupported option\n”);
brk = 0;
break;
}opterr = optind = 1;
while(( c = getopt( argc, argv, “abc:”)) != -1)
switch( c )
{
case ‘a’: printf(“a2\n”);
break;
case ‘b’: printf(“b2\n”);
break;
case ‘c’: printf(“c2 == %s\n”, optarg);
break;
case ‘:’: printf(“will never reach this (2)\n”);
break;
}return 0;
}getopt.c --end
I compile it using qcc -o getopt getopt.c
and ran this as follows:$ ./getopt -c
unsupported option
getopt: option requires an argument – c
$ ./getopt -c 2
unsupported option
c2 == 2
$ ./getopt -c2
unsupported option
getopt: illegal option – 2
$getopt here seems to use another internal static data that
doesn’t get reset on the next function call.
this data resets only when getopt terminates with -1.You will notice however that ‘:’ never gets returned even
when setting opterr to 0 or ‘:’ as documented.
Here’s the magic line from the docs…
If getopt() encounters an option character that isn’t contained in
optstring, it returns the ? character. If it detects a missing
option-argument, it returns : if the first character of optstring
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
is a colon, or ? otherwise. In both cases, getopt() sets optopt to
^^^^^^^^^^
the option character that caused the error.
Colin Burgess <cburgess@qnx.com> wrote:
Here’s the magic line from the docs…
If getopt() encounters an option character that isn’t contained in
optstring, it returns the ? character. If it detects a missing
option-argument, it returns : if the first character of optstring
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
is a colon, or ? otherwise. In both cases, getopt() sets optopt to
^^^^^^^^^^
the option character that caused the error.
uhm. Yes. I should change my lens 
).
another magic line from the docs:
In the example shown before, resetting optind to 1 doesn’t suffice.
actually to reset the internal data of getopt I have to:
optind = 1;
getopt(0, NULL, NULL);
When optind is 1, getopt should automatically reset its internal
data.
–
Wave++