Complex algorithm to extract numbers/number range from a string

Question

I am working on a algorithm where I am trying the following output:

Given values/Inputs:

char *Var = "1-5,10,12,15-16,25-35,67,69,99-105"; int size = 29;

Here "1-5" depicts a range value, i.e. it will be understood as "1,2,3,4,5" while the values with just "," are individual values.

I was writing an algorithm where end output should be such that it will give complete range of output as:

int list[]=1,2,3,4,5,10,12,15,16,25,26,27,28,29,30,31,32,33,34,35,67,69,99,100,101,102,103,104,105;

If anyone is familiar with this issue then the help would be really appreciated. Thanks in advance!

My initial code approach was as:

if(NULL != strchr((char *)grp_range, '-'))
{
    int_u8 delims[] = "-";
    result = (int_u8 *)strtok((char *)grp_range, (char *)delims);

    if(NULL != result)
    {
        start_index = strtol((char*)result, (char **)&end_ptr, 10);
        result = (int_u8 *)strtok(NULL, (char *)delims);
    }

    while(NULL != result)
    {
        end_index = strtol((char*)result, (char**)&end_ptr, 10);
        result = (int_u8 *)strtok(NULL, (char *)delims);
    }

    while(start_index <= end_index)
    {
        grp_list[i++] = start_index;
        start_index++;
    }
}

else if(NULL != strchr((char *)grp_range, ','))
{
    int_u8 delims[] = ",";
    result = (unison_u8 *)strtok((char *)grp_range, (char *)delims);

    while(result != NULL)
    {
        grp_list[i++] = strtol((char*)result, (char**)&end_ptr, 10);
        result = (int_u8 *)strtok(NULL, (char *)delims);
    }
}

But it only works if I have either "0-5" or "0,10,15". I am looking forward to make it more versatile.

Answer 1

You're issue seems to be misunderstanding how strtok works. Have a look at this.

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

int main()
{
        int i, j;
        char delims[] = " ,";
        char str[] = "1-5,6,7";
        char *tok;
        char tmp[256];
        int rstart, rend;

        tok = strtok(str, delims);

        while(tok != NULL) {
                for(i = 0; i < strlen(tok); ++i) {
                        //// range
                        if(i != 0 && tok[i] == '-') {
                                strncpy(tmp, tok, i); 
                                rstart = atoi(tmp);
                                strcpy(tmp, tok + i + 1); 
                                rend = atoi(tmp);
                                for(j = rstart; j <= rend; ++j)
                                        printf("%d\n", j); 
                                i = strlen(tok) + 1;
                        }   
                        else if(strchr(tok, '-') == NULL)
                                printf("%s\n", tok);
                }   

                tok = strtok(NULL, delims);
        }   

        return 0;
}