为什么EOF在我的scanf while循环期间没有终止？

Question

I just started learning C++ and am trying to learn how to use scanf and printf for faster input and output. Here is the code I'm currently working on:

#include <stdio.h>
using namespace std;

int main() {
    int time, record;
    double down, loan;
    while (scanf("%d %lf %lf %d", &time, &down, &loan, &record) != EOF) {
        double value = down + loan;
        double owed = loan;
        double payment = owed/time;

        // current simulated month and depreciation
        int rday, c = 0;
        double temp, dep;
        bool found = false;

        // finds value and owed after records
        while (!found && record > 0) {
            scanf("%d %lf", &rday, &temp);
            // adjusts value and owed to day before listed on record
            while (!found && c <= rday) {
                if (c == rday) {
                    dep = temp;
                }
                value *= 1 - dep;
                if (c > 0) {
                    owed -= payment;
                }
                c++;

                // determines if found date
                if  (owed < value) {
                    found = true;
                }
            }
            record--;
        }

        // finds point where owed < value
        while (!found && value < owed) {
            value *= 1 - dep;
            owed -= payment;
            c++;
        }

        if (c - 1 == 1) {
            printf("%d month\n", c - 1);
        }
        else {
            printf("%d months\n", c - 1);
        }
    }
    return 0;
}

When I run this on Code::Blocks, it prints the correct answers, but the outermost while loop doesn't terminate even when I enter CTRL+Z (I am using Windows). Here is my input:

30 500.0 15000.0 3
0 .10
1 .03
3 .002
12 500.0 9999.99 2
0 .05
2 .1
60 2400.0 30000.0 3
0 .2
1 .05
12 .025
-99 0 17000 1

Here is an image of the what happens:

Error

I've tried changing the loop condition to scanf("%d %lf %lf %d", &time, &down, &loan, &record) == 4 , but the same problem happens. Could someone please explain what the issue with my code is?

Answer 1

In the line

while (scanf("%d %lf %lf %d", &time, &down, &loan, &record) != EOF)

you expect 4 variables to be read into when the read is successful. When scanf is able to successfully extract the data from stdin for all the arguments, it will return 4. Change the check to use that number.

while (scanf("%d %lf %lf %d", &time, &down, &loan, &record) == 4)

Answer 2

这是因为scanf永远不会返回EOF ，所以永远不会满足终止条件。

Answer 3

Thanks for the suggestions and answers, everyone! I figured out the bug. Kind of embarrassing, but it turns out the issue was with the last line of input.