NULL values and "0" strings in C?

I'm having trouble adding a "0" string to a list of strings in C.

With my current code, I'm having trouble distinguishing between a NULL value and a "0" with my current code. I have tried to debug with the if statement (if(pch == "0")) but when I'm outputting it doesn't go into the if statement.

          printf("%c\n",next_line[0]);
          pch = strtok(next_line,",");
          printf("%s\n",pch);
          if(pch == "0"){
            printf("NULL VALUE");
            strcpy(strs[i],pch);
            i++;
            pch = strtok(NULL, ",");
          }
          while(pch != NULL){
            strcpy(strs[i],pch);
            i++;
            pch = strtok(NULL, ",");
          }
          //go on to print values

the input is: 0,1,03:48:13,9 I never make it past the first character. What can I do to keep my code? Can I maybe change

     pch = strtok(NULL, ","); 
    to pch = strtok(SOMEOTHERVALUE, ",");?