使用文件c ++的输入输出时出现问题

Question

实现此代码时

当黑屏弹出时程序运行它没有其他东西等待了一段时间没有发生任何事情没有完成没有给我进程返回0知道它已经完成如果有人可以告诉我输出文件是空的这里有什么问题

#include<iostream>
#include<fstream>
#include<iomanip>

using namespace std;

int main()
{
ifstream file;
ofstream out;

file.open("coinsCoint.txt");
out.open("1234567.txt");

int pennis,nickle,dime,quarter,sum=0;
float total;

while(!file.eof())
{
    file >> pennis >> nickle >> dime >> quarter;

    sum+=pennis+nickle*5+dime*10+quarter*25;

    total=sum/100.0;

}

out << "Total amount collected is: $" << fixed << showpoint << 
setprecision(2) << total;

file.close();
out.close();

return 0;

}

Answer 1

#include<iostream>
#include<fstream>
#include<iomanip>

using namespace std;

int main()
{
    ifstream file;
    ofstream out;

    file.open("coinsCoint.txt");

    int pennis = 0, nickle = 0, dime = 0, quarter = 0, sum = 0;
    float total = 0.0;

    /* check if file is opened */
    if (file.is_open()){

        while (!file.eof())
        {
            file >> pennis >> nickle >> dime >> quarter;
            cout << "pennis " << pennis << endl;
            cout << "nickle " << nickle << endl;
            cout << "dime " << dime << endl;
            cout << "quarter " << quarter << endl;

            sum += pennis + nickle * 5 + dime * 10 + quarter * 25;
            total = sum / 100.0;
            cout << "total " << total;
        }
        file.close();
    }
    /* return if error in file open */
    else {
        cout<< "can not open given file";
        return 0;
    }
    out.open("1234567.txt");

    if (out.is_open()){
        out << "Total amount collected is: $" << fixed << showpoint <<
            setprecision(2) << total;
        out.close();
    }
    return 0;
}

类似教程https://www.uow.edu.au/~lukes/TEXTBOOK/notes-cpp/io/readtextfile.html

你应该经常检查文件是否被is_open()正确打开

您需要使用cout << 打印来控制“黑屏”

文件看起来像

1
2
3
4

输出应该是这样的

pennis 1
nickle 2
dime 3
quarter 4
total 1.41Press <RETURN> to close this window...