reading large lists through stdin in C

Question

If my program is going to have large lists of numbers passed in through stdin, what would be the most efficient way of reading this in?

The input I'm going to be passing into the program is going to be of the following format:

3,5;6,7;8,9;11,4;; 

I need to process the input so that I can use the numbers between the colons (i.e I want to be able to use 3 and 5, 6 and 7 etc etc). The ;; indicates that it is the end of the line.

I was thinking of using a buffered reader to read entire lines and then using parseInt.

Would this be the most efficient way of doing it?

Answer 1

This is a working solution
One way to do this is to use strtok() and store the values in an array. Ideally, dynamically allocated.

 int main(int argc, char *argv[])
{
    int lst_size=100;
    int line_size=255;

    int lst[lst_size];
    int count=0;

    char buff[line_size];
    char * token=NULL;
    fgets (buff, line_size, stdin); //Get input

Using strtok by passing ',' and ';' as deleminator.

    token=strtok(buff, ";,");
    lst[count++]=atoi(token); 
    while(token=strtok(NULL, ";,")){
          lst[count++]=atoi(token);
    }

Finally you have to account for the double ";;" by reducing the count by 1, because atoi(token) will return 0 for that case and store it in the nth index. Which you don't want.

  count--;

}