文件流与标准流

#include <iostream>
using namespace std;

int main(){
	FILE *fin, *fout;
	fin = fopen("in.txt", "rb");
	fout = fopen("out.txt", "wb");

	int x = 0;
	int s = 0;
	while(fscanf(fin, "%d", &x) == 1){
		s += x;
	}
	
	int y;
	cin >> y;
	s += y;

	fprintf(fout,"%d", s);
	fclose(fin);
	fclose(fout);

	return 0;
}

从in.txt读取1 2 3 4

从键盘读取5

加和

输出到out.txt