CS 320 flag parsing

flagparse-example.c

	// parse command line arguments for flags (i.e. help and output filename)
	for (i = 1; i < argc; i++) {
		if (argv[i][0] == '-') { /* flag */
			if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
				usage(argv[0]);
				exit(EXIT_SUCCESS);
			}

			if (strcmp(argv[i], "-o") == 0) {
				if (i >= argc - 1) {
					fprintf(stderr, "Missing output file argument.\n");
					exit(EXIT_FAILURE);
				} else {
					char output_file[255];
					int result = sscanf(argv[++i], "%255s", output_file);
					if (result != 1) {
						fprintf(stderr, "Error reading output file parameter: %s\n", argv[i]);
						exit(EXIT_FAILURE);
					}
					output = fopen(output_file, "w");
				}
			}
		}
	}