#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;
int main() {
bool done = false;
cout << setprecision(20) << endl;
ifstream infile("in.txt");
ifstream outfile("out.txt");
while(!infile.eof()) {
int sign = 1;
double pi = 0;
long n;
infile >> n;
for(long i = 1; i < n; i += 2) {
pi += sign/(double)i;
sign = -sign;
}
pi *= 4;
cout << "value of pi for n = " << n << " is " << pi << endl;
}
return 0;
}
这将从文件中读取并打印到控制台,但是我无法获取代码以打印到输出文件。我尝试过]]
outfile<< "value of pi for n = " << n << " is " << pi << endl;
但是那似乎不起作用
##
它不会写入文件,因为您将outfile
定义为std::ifstream
ifstream
用于输入文件。将其定义为ofstream
,它应该可以工作。
示例: