Write a function expand(s1,s2) that expands shorthand notation like a-z in the string s1 into the equivalent complete list abc—-xyz in s2.Allow for letters of either case and digits, and be prepared to handle cases like a-b-c and a -z0-9 and -a-z.Arrange that a leading or trailing – is taken literally.

/*expand: expand shorthand notation in s1 into string s2 */
void expand(char s1[], char s2[]){
     char c;
     int i, j;
     
     i =j = 0;
     while((c =s1[i++]) != '\0')   /* fetch a char from s1[] */
         if (s1[i] == '-' && s1[i+ 1] >= c){
           i++;
           while(c < s1[i]) /* expand shorthand   */
                s2[j++] = c++;
         }else
               s2[j++] = c;    /* copy the character */
    s2[j] = '\0';
}

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