Question

I have a String like this:

"00:00:00 000~00:02:00 0000|~00:01:00 0000;00:01:00 0000~",

I want to get each of the items like "00:00:00 000".

My idea is that first, split the string by ";", then split by "|", and finally split by "~".

But the problem is that I can’t get it if it’s null, such like "00:01:00 0000~", the part after "~", I wanna get it and set a default value to it then store it somewhere else, but the code doesn’t work. What is the problem?

Here is my code:

int main(int argc, char *argv[])
{

   char *str1, *str2, *str3, *str4, *token, *subtoken, *subt1, *subt2;
   char *saveptr1, *saveptr2, *saveptr3;
   int j;

   for (j = 1, str1 = argv[1]; ; j++, str1 = NULL) {
       token = strtok_r(str1, ";", &saveptr1);
       if (token == NULL)
           break;
       printf("%d: %s\n", j, token);

       int flag1 = 1; 
       for (str2 = token; ; str2 = NULL) {
           subtoken = strtok_r(str2, "|", &saveptr2);
           if (subtoken == NULL)
               break;
           printf("  %d: --> %s\n", flag1++, subtoken);
           int flag2 = 1;
           for(str3 = subtoken; ; str3 = NULL) {
                subt1 = strtok_r(str3, "~", &saveptr3);
                if(subt1 == NULL) {
                    break;
                }
                printf("      %d: --> %s\n",flag2++, subt1);
           }
       }
   }

   exit(EXIT_SUCCESS);
} /* main */

Answer 1

Instead of splitting the string, it might be more suitable to come up with a simple finite state machine that parses the string. Fortunately, your tokens seem to have an upper limit on their length, which makes things a lot easier:

Iterate over the string and distinguish four different states:

• current character is not a delimiter, but previous character was (start of token)
• current character is a delimiter and previous character wasn’t (end of token)
• current and previous character are both not delimiters (store them in temporary buffer)
• current and previous character are both delimiters (ignore them, read next character)

It should be possible to come up with a very short (10 lines?) and concise piece of code that parses the string as specified.