ex-3-3.c

/*
 * Exercise 3-3. Write a function expand(s1,s2) that expands shorthand 
 * notations 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.  
 */

#include <stdio.h>

void expand(char s1[], char s2[])
{
	char c;
	int i, j;
	i = j = 0;
	while ((c = s1[i++]) != '\0')
	{
		if (s1[i] == '-' && s1[i + 1] >= c)
		{
			i++;
			while (c < s1[i])
				s2[j++] = c++;
		}
		else
			s2[j++] = c;
		s2[j] = '\0';
	}
}

void test2()
{
    char *s[] = { "a-z-", "z-a-", "-1-6-",
                  "a-ee-a", "a-R-L", "1-9-1",
                  "5-5", NULL };
    char result[100];
    int i = 0;
    
    while ( s[i] ) {
        
        /*  Expand and print the next string in our array s[]  */
        
        expand(s[i], result);
        printf("Unexpanded: %s\n", s[i]);
        printf("Expanded  : %s\n", result);
        ++i;
    }
}	

int main(void)
{
	test2();
	return 0;
}