ADD file via upload

daochu.cpp

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+#include<iostream>
+#include<string>
+#include<fstream>
+#include"book.h"
+#include"library.h"
+using std::cout;
+using std::cin;
+using std::endl;
+extern Book booklist[50];
+extern int num;
+void wxy::daochu()
+{
+	std::ofstream ofile("booklist.txt");
+	ofile << num << '\n';
+	for (int i = 0; i < num; i++)
+	{
+		ofile << booklist[i].Name << ' ' << booklist[i].Auther << ' ' << booklist[i].amount << '\n';
+	}
+	ofile.close();
+}