Question

I don’t understand why the code below fail :

char    toto[54], titi[54]; //I already tried with allocations

sscanf_s(line, "%s-%s", &toto, &titi, sizeof(toto) + sizeof(titi));

or

sscanf_s(line, "%s-%s", &toto, &titi, sizeof(toto) + sizeof(titi));

My problem is only with strings (float, int, double etc. its ok) and I use Visual 2010.

Does anyone have an idea?
Thanks a lot in advance for your answer.

Answer 1

From the sscanf_s() reference page:

The sscanf_s function reads data from buffer into the location given by each argument. The arguments after the format string specify pointers to variables with a type that corresponds to a type specifier in format. Unlike the less secure version sscanf, a buffer size parameter is required when using the type field characters c, C, s, S and [. The buffer size in characters must be supplied as an additional parameter after each buffer which requires it. For more information, see scanf_s, _scanf_s_l, wscanf_s, _wscanf_s_l and scanf Type Field Characters.

Meaning each buffer must be followed by its size:

sscanf_s(line, "%s-%s", toto, sizeof(toto), titi, sizeof(titi));

Additionally, - is not a whitespace character will not act as a terminator for "%s" format specifier so if line contained hello-world then it would be read into toto and titi would not be assigned. To use - as a terminator use a scan set:

if (2 == sscanf_s(line, "%[^-]-%s", toto, sizeof(toto), titi, sizeof(titi)))
{
    /* Both 'toto' and 'titi' where assigned. */
}