C++文件读写

#include <fstream>
using namespace std;
const int cutoff = 6000;
const float rate1 = 0.3;
const float rate2 = 0.6;
int main() {
    ifstream infile;
    ofstream outfile;
    int income, tax;
    infile.open("income.in");
    outfile.open("tax.out");
    while (infile >> income) {
        if (income <= cutoff)
            tax = rate1 * income;
        else
            tax = rate2 * income;
        outfile << "Income = " << income << " greenbacks\n" << "Tax = " << tax << " greenbacks\n";
    }
    infile.close();
    outfile.close();
    return 0;
}

测试文件是否打开

#include <iostream>
#include <fstream>
using namespace std;
int main() {
    ifstream inFile;
    ofstream outFile
    int i;
    int j;
    inFile.open("input.dat");
    if (!inFile) {
        cerr << "Unable to open input" << endl;
        exit(0);
    }
    ...
}