#include <stdio.h>
#include <ctype.h>

#define MAXLEN 30

void expand(char s1[], char s2[]);

int main()
{
    char in[MAXLEN] = "-A-Z1-9\0";
    char out[MAXLEN];

    printf("s1 = %s\n", in);
    expand(in, out);
    printf("s2 = %s\n", out);

    return 0;
}
void expand(char s1[], char s2[])
{
    int i, j;
    char t;

    for (i = 0, j = 0; s1[i] != '\0'; i++)
    {
        if ( s1[i] == '-' )
        {
            if ( (isdigit(s1[i-1]) && isdigit(s1[i+1]) && (s1[i-1]<s1[i+1])) ||
                 (islower(s1[i-1]) && islower(s1[i+1]) && (s1[i-1]<s1[i+1])) ||
                 (isupper(s1[i-1]) && isupper(s1[i+1]) && (s1[i-1]<s1[i+1])) )
                    for (t = (char)(s1[i-1]+1); t < s1[i+1]; t++)
                        s2[j++] = t;
            else
                s2[j++] = s1[i];
        }
        else
            s2[j++] = s1[i];
    }
    s2[j] = '\0';
}