Question

The c++ question：

Assume that there is a valid file cards.txt in the current directory which contains 5 valid int values, each on its own line. Write a function which reads all the values from the file and prints out the message “Lucky 7!” to the screen for every 7 it sees. Your function must have the following signature:

void printSevens();

Answer 1

#include <iostream>
#include <fstream>

using namespace std;

void printSevens();

int main() {
    printSevens();
    return 0;
}

void printSevens() {
    ifstream in("cards.txt");
    if (in.is_open()) {
        int n;
        while (in >> n) {
            if (n == 7)
                cout << "Lucky 7!" << endl;
        }
        in.close();
    } else {
        cout << "cards.txt does not exists!" << endl;
    }
}