C - How to split a string with delimiter when sometimes there are no values between delimiter?

Question

I am trying to split a string as follows: 1.97E+13,1965.10.30,12:47:01 AM,39.1,23,greece,,,,,10,4.8,4.6,4.6,4.8,4.6,4.7

I am using strtok and giving , as a delimiter but since there are no values between some commas I get a segmentation fault.

What is the correct way to assign null values to consecutive commas?

Answer 1

Instead of strtok use functions strspn and strcspn.

Here is a demonstration program.

#include <stdio.h>
#include <string.h>

int main( void )
{
    const char *s = "1.97E+13, 1965.10.30, 12:47 : 01 AM, 39.1, 23, "
        "greece, , , , , 10, 4.8, 4.6, 4.6, 4.8, 4.6, 4.7";

    const char *delin = ",";

    for (const char *p = s; *p; p += *p != '\0')
    {
        size_t n = strcspn( p, delin );
        if (n == 0)
        {
            puts( "empty" );
        }
        else
        {
            printf( "\"%.*s\"\n", ( int )n, p );
        }

        p += n;
    }
}

The program output is

"1.97E+13"
" 1965.10.30"
" 12:47 : 01 AM"
" 39.1"
" 23"
" greece"
" "
" "
" "
" "
" 10"
" 4.8"
" 4.6"
" 4.6"
" 4.8"
" 4.6"
" 4.7"