Re: quick question

[Ben Rudiak-Gould <Benjamin dot Rudiak-Gould at cl dot cam dot ac dot uk>]

Jim Stapleton wrote:
> char *superstring = (char*)malloc(sizeof(int) * 2 + sizeof(char) * string_size);
>
> string lenght: (int)*(superstring - sizeof(int))
> string allocated: (int)*(superstring - sizeof(int) * 2)

Suggestion:

    typedef struct {
        size_t allocated, length;
        char contents[1];
    } SuperString;

    SuperString *superstring =
        malloc(offsetof(SuperString,contents) + string_size);

Incidentally, C and C++ both guarantee sizeof(char)==1, and in C it's 
considered good practice to omit explicit casts from (void*) in this 
situation, since the redundancy can be a source of error. (But in C++ you 
can't omit them.)

-- Ben