/* 
 * Simple contrived example of formatted I/O on files:
 * Read integers from input, sum, write sum to output file.
 * Filenames given as command-line arguments.
 */
#include <stdio.h>

int main(int argc, char *argv[]) {
	if (argc != 3) {
		printf("two args\n");
		return 1;
	}
	FILE * infile = fopen(argv[1], "r");
	if (infile == NULL) {
		printf("cannot open input\n");
		return 1;
	}
	FILE * outfile = fopen(argv[2], "w");
	if (outfile == NULL) {
		printf("cannot open output\n");
		return 1;
	}

	int n;
	int sum = 0;
	while (fscanf(infile, "%d", &n) == 1) {
		sum += n;
	}
	fprintf(outfile, "%d\n", sum);

	fclose(infile);
	fclose(outfile);
	return 0;
}