#include <string.h>
#include <ctype.h>

const char *alphabet = "abcdefghijklmnopqrstuvwxyz";

/*
 * returns index of inchar in alphabet (0 to 25), or -1 if not alphabetic
 */
int alpha_index(int inchar) {
	char *p;
	if ((p = strchr(alphabet, tolower(inchar))) != NULL) {
		return p-alphabet;
	} 
	else {
		return -1;
	}
}