Little problem with a delirant program

[Army1987]

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
char *_(char *str1, char *str2)
{
char *res;
res = malloc((strlen( str1)+strlen(st r2))*sizeof(cha r));
strcpy(res, str1);
strcpy(res+strl en(str1), str2);
return res;
}

int main(void)
{
char a[] = "\nHey man look at me rockin' now\nI'm on the ";
char b[] = "Danny and Lisa";
char c[] = "\nThey take me away from";
char *d = _(_(a,"radio"), _(a,"video"));
char *e = _(d,_(" with ",b));
char *g = _("\nThe strangest places\nSweet ",b);
char *h = _(c,g);
char *i = _(_(h,c),_(h,c) );
char *j = _(e,i);
char *k = _(_(d,j),_(j,e) );
char *l = _(_(k,h),_(d,e) );
puts(++l); /* ++l gets rid of the spurious newline character at the
beginning */
return 0;
}

Why does this program add a spurious '1' after each occurrence of the last
line of the chorus? (i.e. "I'm on the video with Danny and Lisa1").
(I said it was delirant... But I fear that for copyright problems I won't be
able to sumbit a modification of this to the next IOCCC...)
T.I.A.

--
#include <stdio.h>
main()
{
printf("\n\n--\nArmy1987");
}

[Eric Sosman]

Army1987 wrote:

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
char *_(char *str1, char *str2)

Don't do that. Identifiers beginning with `_' are
reserved. There are a few contexts in which they are not
reserved, but this isn't one of them.

{
char *res;
res = malloc((strlen( str1)+strlen(st r2))*sizeof(cha r));
strcpy(res, str1);
strcpy(res+strl en(str1), str2);

This is probably where your program goes off the rails;
perhaps one line earlier if str2 has zero length. I thought
this matter would be covered in the FAQ -- but perhaps it's
just a Frequently Committed Error rather than a Frequently
Asked Question, since the very asking of the question implies
awareness of the issue.

Anyhow, the immediate error is that a string whose length
is N characters requires N+1 bytes of storage.

return res;
}

int main(void)
{
char a[] = "\nHey man look at me rockin' now\nI'm on the ";
char b[] = "Danny and Lisa";
char c[] = "\nThey take me away from";
char *d = _(_(a,"radio"), _(a,"video"));
char *e = _(d,_(" with ",b));
char *g = _("\nThe strangest places\nSweet ",b);
char *h = _(c,g);
char *i = _(_(h,c),_(h,c) );
char *j = _(e,i);
char *k = _(_(d,j),_(j,e) );
char *l = _(_(k,h),_(d,e) );
puts(++l); /* ++l gets rid of the spurious newline character at the
beginning */
return 0;
}

Why does this program add a spurious '1' after each occurrence of the last
line of the chorus? (i.e. "I'm on the video with Danny and Lisa1").
(I said it was delirant... But I fear that for copyright problems I won't be
able to sumbit a modification of this to the next IOCCC...)

It wouldn't win. The IOCCC seeks obfuscations far more
original than just using an unusual name, especially an unusual
name that isn't yours to use.

--
Eric Sosman
es*****@acm-dot-org.invalid

[Malcolm McLean]

"Army1987" <pl********@for .itwrote in message n

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
char *_(char *str1, char *str2)
{
char *res;
res = malloc((strlen( str1)+strlen(st r2))*sizeof(cha r));

^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^
No room for terminating nul.

strcpy(res, str1);
strcpy(res+strl en(str1), str2);

^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^
Undefined behaviour here.

return res;
}

int main(void)
{
char a[] = "\nHey man look at me rockin' now\nI'm on the ";
char b[] = "Danny and Lisa";
char c[] = "\nThey take me away from";
char *d = _(_(a,"radio"), _(a,"video"));
char *e = _(d,_(" with ",b));
char *g = _("\nThe strangest places\nSweet ",b);
char *h = _(c,g);
char *i = _(_(h,c),_(h,c) );
char *j = _(e,i);
char *k = _(_(d,j),_(j,e) );
char *l = _(_(k,h),_(d,e) );
puts(++l); /* ++l gets rid of the spurious newline character at the
beginning */
return 0;
}

Why does this program add a spurious '1' after each occurrence of the last
line of the chorus? (i.e. "I'm on the video with Danny and Lisa1").
(I said it was delirant... But I fear that for copyright problems I won't
be able to sumbit a modification of this to the next IOCCC...)
T.I.A.

--
#include <stdio.h>
main()
{
printf("\n\n--\nArmy1987");
}

--
Free games and programming goodies.
http://www.personal.leeds.ac.uk/~bgy1mm

[Army1987]

I've found the problem. For the memory allocated by the function _(str1,
str2) to contain the concatenation of str1 and str2, its size should be
strlen(str1) + strlen(str2) + 1, as one byte is needed to contain the
terminator '\0' character.

So I replaced the assignment in the function body with:
res = malloc((strlen( str1)+strlen(st r2)+1)*sizeof(c har));

Probably, in the former version of the program the '\0' byte after one of
these strings was somehow overwritten as it was not "allotted" for that
string.

BTW, I meant "delirious" . I should have checked my English besides my C...

[Army1987]

It wouldn't win. The IOCCC seeks obfuscations far more

original than just using an unusual name, especially an unusual
name that isn't yours to use.

I used that just because it was the shortest identifier which couldn't clash
with a letter (as I didn't know beforehand how many letters I had to use).
Of course I could just use a capital letter, but I didn't know about
reserved identifiers, and I thougth _ was cooler... ;-)
Of course, if I were really going to submit it to IOCCC, I'd brutally deface
it first... (I was just joking, I started learning C just about two months
ago... And I've seen some programs by the past winners of IOCCC and I really
think some of them really need to get a life...)

[Martin Ambuhl]

Army1987 wrote:

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
char *_(char *str1, char *str2)

^^^
very, very naughty. Don't do this. It is evil.

{
char *res;
res = malloc((strlen( str1)+strlen(st r2))*sizeof(cha r));

Not only is sizeof(char) superfluous here (it's 1 by definition),
you don't allocate enough space:
res = malloc(strlen(s tr1) + strlen(str2) + 1);
And, of course, you should check the return value from malloc.

strcpy(res, str1);
strcpy(res+strl en(str1), str2);
return res;
}

int main(void)
{
char a[] = "\nHey man look at me rockin' now\nI'm on the ";
char b[] = "Danny and Lisa";
char c[] = "\nThey take me away from";
char *d = _(_(a,"radio"), _(a,"video"));
char *e = _(d,_(" with ",b));
char *g = _("\nThe strangest places\nSweet ",b);
char *h = _(c,g);
char *i = _(_(h,c),_(h,c) );
char *j = _(e,i);
char *k = _(_(d,j),_(j,e) );
char *l = _(_(k,h),_(d,e) );
puts(++l); /* ++l gets rid of the spurious newline character at the
beginning */
return 0;

Are you _sure_ you want to return before freeing all those arrays
that your (incorrectly) allocated?

}

Why does this program add a spurious '1' after each occurrence of the last
line of the chorus?

Since your allocation is broken, you're unlucky that your program didn't
crash instead.

(i.e. "I'm on the video with Danny and Lisa1").
(I said it was delirant... But I fear that for copyright problems I won't be

^^^^^^^^
What language is this a word in? And when did you say it? What
does it mean?

able to sumbit a modification of this to the next IOCCC...)

Please don't submit broken or illegal code to IOCCC. The woeld doesn't
need any more of either.

T.I.A.

Bite me.

[Army1987]

Are you _sure_ you want to return before freeing all those arrays that

your (incorrectly) allocated?

Isn't my OS supposed to free them all immediately after main() returns?
(I refer to the corrected version, with
res = malloc(strlen(s tr1)+strlen(str 2)+1);
and maybe even
if (res==NULL) exit(EXIT_FAILU RE);
now.)

>(I said it was delirant... But I fear that for copyright problems I won't
be

^^^^^^^^
What language is this a word in? And when did you say it? What
does it mean?

I meant "delirious" , sorry. I said it in the object line.

[Old Wolf]

On Mar 19, 7:38 am, Eric Sosman <[e-mail] e:

Army1987 wrote:

char *_(char *str1, char *str2)

Don't do that. Identifiers beginning with `_' are
reserved. There are a few contexts in which they are not
reserved, but this isn't one of them.

I thought such identifiers were only reserved if they started
with _ followed by an uppercase letter (or another _).

[Malcolm McLean]

"Army1987" <pl********@for .itwrote in message

> Are you _sure_ you want to return before freeing all those arrays that
your (incorrectly) allocated?

Isn't my OS supposed to free them all immediately after main() returns?
(I refer to the corrected version, with
res = malloc(strlen(s tr1)+strlen(str 2)+1);
and maybe even
if (res==NULL) exit(EXIT_FAILU RE);
now.)

If an OS doesn't free memory on exit either
You are running a useless operating system that should be traded in
immediately
or
You are on some small system that will only run a limited subset of
programs, and isn't meant to be a general-purpose computer.

However it is a good habit to free memory after you are done with it. In big
programs it is essential.
--
Free games and programming goodies.
http://www.personal.leeds.ac.uk/~bgy1mm

[pete]

Old Wolf wrote:

>
On Mar 19, 7:38 am, Eric Sosman <[e-mail] e:

Army1987 wrote:

char *_(char *str1, char *str2)

Don't do that. Identifiers beginning with `_' are
reserved. There are a few contexts in which they are not
reserved, but this isn't one of them.

I thought such identifiers were only reserved if they started
with _ followed by an uppercase letter (or another _).

The rules are complicated enough so that I just simply
avoid writing identifiers that start with underscores.

N869
7.1.3 Reserved identifiers
[#1]
-- All identifiers that begin with an underscore are
always reserved for use as identifiers with file scope
in both the ordinary and tag name spaces.

--
pete