reading the remainder of a string with sscanf

Question

I'm trying to read a string which consists of a set of numbers followed by a string, wrapped with some other basic text.

In other words, the format of the line is something like this:

Stuff<5,10,-5,8,"Test string here.">

Naively, I tried:

sscanf(str,"Stuff<%d,%d,%d,%d,\"%s\">",&i1,&i2,&i3,&i4,str2);

But after some research I discovered %s is supposed to stop parsing when it gets to a whitespace character. I found this question, but none of the answers addresses the problem I have: the string could contain any character in it, including newline characters and properly escaped quotes. The latter is not a problem, if I can just get sscanf to put everything after the first quote in the pre-allocated buffer I provide, I can strip the end off myself.

But how do I do this? I can't use %[] because it requires something in it to terminate the string, and the only thing I want to terminate it is the null terminator. So I thought, "Hey, I'll just use the null terminator!" But %[\0] made the compiler grumpy:

warning: no closing ‘]’ for ‘%[’ format
warning: embedded ‘\0’ in format
warning: no closing ‘]’ for ‘%[’ format
warning: embedded ‘\0’ in format

Using something like %*c won't work either, because I don't know exactly how many characters need to be taken. I tried passing strlen(str) since it will be less than that, but sscanf returns 4 and nothing is put into str2, suggesting that perhaps because the length was too long it gave up and didn't bother.

Update: I guess I could do something like:

sscanf(str,"Stuff<%d,%d,%d,%d,\"%n",&i1,&i2,&i3,&i4,&n);
str2 = str+n;

Answer 1

Your update seems to be a good answer. I was going to suggest strchr to find the location of the first quote char, after using sscanf to get i1 thru i4. Side note, you should always check the return value from sscanf to make sure that the conversions worked. This is even more important with your suggested answer, since n will be left uninitialized if the first four conversions aren't successful.

Answer 2

Scan for '\"', then for everything not '\"', then '\"' again.

Be sure to check sscanf() result and limit how long the test string may be.

char test_string[100];
int n = 0;
if (sscanf(str, "Stuff<%d,%d,%d,%d, \"%99[^\"]\"> %n",
      &i1, &i2, &i3, &i4, test_string, &n) == 5 && str[n] == '\0') Good();

---

Your attempt using "...%[\0]...", from sscanf() point-of-view, is "...%[".
Everything in the format from "\0" on is ignored.

Using the int n = 0, appending " %n" to the format string, appending &n to the parameters and checking str[n] == '\0' is a neat trick with sscanf() to insure the entire line parsed correctly. Note: "%n" does not add to sscanf() result.

Answer 3

This is not the only way to achieve what you want to achieve, but probably the neatest way to do it: You'll need to use the scansets. I won't tell you the solution directly with this answer, I'll explain how to use scansets as far as I know them, and you'll hopefully be able to do it yourself.

Scansets %[...] are like %s when it comes to assignment, they interpret values as characters and store them into character arrays. %s is whitespace-terminated, %[...] is the flexible version of that.

There are two ways of using the scanset, first one being without a preceding caret ^, second one being with a preceding caret ^.

When you use scanset without the preceding caret ^, the characters you put inside the brackets will be the only ones that will be read, stored and then left behind. As soon as scanf encounters a non-matching character, that %[...] will be over. For example:

// input: asdasdasdwasdasd
char s[100] = { 0 };
scanf( "%[das]", s );
printf( "%s", s );
// output: asdasdasd

When you use scanset with the preceding caret ^, the search is inversed. It reads, stores and leaves behind every character until it reaches any one of the characters that you've put down after the preceding caret ^. Example:

// input: abcdefgh^kekQ
char s[100] = { 0 };
scanf( "%[^Q^]", s );
printf( "%s", s );
// output: abcdefgh

Beware, remaining characters is still to be read inside the stream, the file pointer won't get beyond the character which caused termination. I.e. for the first one, getchar( ); would give a 'w', and for the second one it would give a '^'.

I hope this will be enough. If you still cannot find your way out, ask away, I can give you a solution.