/* nullcipher.c
 * By Feky, January 2008 */
 
 #include <stdio.h>
 #include <string.h>
 
 void parse(char *);
 
 void parse(char *line) {
	 size_t sz = strlen(line);
	 unsigned int i;
	 char prev = ' ';
	 
	 for(i = 0; i < sz; i++) {
		 if(!isalnum(line[i]) && isalnum(prev))
			 printf("%c", tolower(prev));
		 prev = line[i];
	 }
 }
 
 int main(int argc, char **argv) {
	 FILE *file;
	 char ln[512];
	 
	 if(argc != 2) {
		 fprintf(stderr, "%s <file>\n", argv[0]);
		 return -1;
	 }
	 
	 file = fopen(argv[1], "r");
	 if(file == NULL) {
		 fputs("Failed to open file.\n", stderr);
		 return -1;
	 }
	 
	 while(!feof(file)) {
	         memset(ln, '\0', 512);
		 fgets(ln, 512, file);
		 parse(ln);
	 }
	 
	 putchar('\n');
	 fclose(file);
	 
	 return 0;
 }