Re: [Dev-C++] Allocation problem

[Per W. <pw...@ia...>]

Nice to ear.

One thing. Since source code is so very unforgiving about even the
smallest spelling errors it is always a good idea to cut and paste any
source code in the mails.

/Per W

On Wed, 24 Sep 2003, Matthews wrote:

> Thanks a lot Per.  It's working perfectly now.  And the
> >  info.input = (char*)malloc(...);
> was a mistype by me in the email, which is why I got no errors :p
>
> At 11:19 PM 21/09/2003 +0200, Per Westermark wrote:
> >prj_info.input is a pointer to a pointer to char.
> >
> >If you want to store 10 lines in it:
> >
> >info.input = (char**)malloc(10*sizeof(char*));
> >info.input[0] = (char*)malloc(sizeof(char)*(strlen("mystr1")+1));
> >...
> >info.input[9] = (char*)malloc(sizeof(char)*(strlen("mystr10")+1));
> >
> >strcpy(info.input[0],"mystr1");
> >...
> >strcpy(info.input[9],"mystr10");
> >
> >Question: Don't you ever try to get the compiler to generate as many
> >warnings as possible, and then check up on the warnings?
> >
> >The compiler would definitely become a bit worried when you do:
> >  info.input = (char*)malloc(...);
> >since you are typecasting to the wrong type.
> >
> >Take two steps back and think a bit about your code and what you want to
> >do. Check up on all data types, and exactly what you allocate.
> >
> >That little realloc() line you have is very, very interesting. You are
> >reallocating the wrong thing - did you intend to reallocate the array
> >of pointers to text strings, or a specific string buffer in the array?
> >- and you are forgetting that the new pointer is the RETURN VALUE of the
> >realloc() call.
> >
> >/Per W
> >
> >On Sat, 20 Sep 2003, Matthews wrote:
> >
> >> Still giving me the same crash :\
> >>
> >> At 11:32 AM 20/09/2003 +0200, Per Westermark wrote:
> >> >When you allocate buffers for strings, you must allocate room for
> >> >strlen(str)+1
> >> >characters, or the termination character '\0' will not fit.
> >> >
> >> >/Per W
> >> >
> >> >On Fri, 19 Sep 2003, Matthews wrote:
> >> >
> >> >> I'm working on a program to generate makefiles for me, and I
> currently have
> >> >> it set up to read different sections of a file to generate the options.
> >> >> One section is %input, which has a list of filenames to include, eg.
> >> >>
> >> >> prj.txt
> >> >>
> >> >> %input
> >> >> main.c
> >> >> vid.c
> >> >> gui.c
> >> >>
> >> >> I read these into a struct organized like so:
> >> >>
> >> >> struct prj_info
> >> >> {
> >> >>   ...
> >> >>   char **input;
> >> >>   ...
> >> >> }
> >> >>
> >> >> And I allocate space based on how many files there are (an array of
> >> >> strings, basically)
> >> >>
> >> >> My problem is that I get errors when running the following C code:
> >> >>
> >> >> if(!strncmp("%include",t,strlen(t)-1))
> >> >> {
> >> >>   count = 0;
> >> >>   skip_line(buf);
> >> >>   getword(buf,t);
> >> >>   longest_length = strlen(t);
> >> >>   info.input = (char *)malloc((sizeof(char)*longest_len)*1);
> >> >>   if(!info.input)
> >> >>   {
> >> >>     printf("OH NOS\n");
> >> >>     return 0;
> >> >>   }
> >> >>   //CRASH HERE
> >> >>   strcpy(info.input[count],t);
> >> >>   while(*buf!='%')
> >> >>   {
> >> >>     while(*buf=='#'||isspace(*buf)) skip_line(buf);
> >> >>     getword(buf,t);
> >> >>     if(strlen(t)>longest_length) longest_length = strlen(t);
> >> >>     count++;
> >> >>     realloc(info.input,(sizeof(char)*longest_length)*count);
> >> >>     if(!info.input)
> >> >>     {
> >> >> 	printf("ERR0RZ\n");
> >> >> 	return 0;
> >> >>     }
> >> >>     strcpy(info.input[count],t);
> >> >>     skip_line(buf);
> >> >>   }
> >> >> }
> >> >>
> >> >> Buf is the dumped contents of a file (like prj.txt), getword() places a
> >> >> word from buf into t and skip_line() skips to the next line in buf.
> >> >>
> >> >> The code compiles fine, but crashes at the first strcpy().  Any help
> would
> >> >> be appreciated.
> >> >>
> >> >>
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