Merge pull request #233 from Falling-in-W-sweetty/patch-4

Update 12-9.cpp

Author: Light-City

practical_exercises/10_day_practice/day10/文件例题/12-9.cpp

@@ -22,20 +22,20 @@ class Employee{
 };
 
 int main(){
-    ofstream out("D:/Employee.dat",ios::out);	//定义随机输出文件
-    Employee e1(1,"张三",23,2320);
-    Employee e2(2,"李四",32,3210);
-    Employee e3(3,"王五",34,2220);
-    Employee e4(4,"刘六",27,1220);
-    out.write((char*)&e1,sizeof(e1));		//按e1,e2,e3,e4顺序写入文件
+    ofstream out("D:/Employee.dat",ios::out);	//定义随机输出文件
+    Employee e1(1,"张三",23,2320);
+    Employee e2(2,"李四",32,3210);
+    Employee e3(3,"王五",34,2220);
+    Employee e4(4,"刘六",27,1220);
+    out.write((char*)&e1,sizeof(e1));		//按e1,e2,e3,e4顺序写入文件
     out.write((char*)&e2,sizeof(e2));
     out.write((char*)&e3,sizeof(e3));
     out.write((char*)&e4,sizeof(e4));
 
-     //下面的代码将e3（即王五）的年龄改为40岁   
-    Employee e5(3,"王五",40,2220);
-    out.seekp(3*sizeof(e1));		//指针定位到第3（起始为0）个数据块
-    out.write((char*)&e5,sizeof(e5));	//将e5写到第3个数据块位置，覆盖e3
-    out.close();			//关闭文件
+     //下面的代码将e3（即王五）的年龄改为40岁   
+    Employee e5(3,"王五",40,2220);
+    out.seekp(2*sizeof(e1));		//指针定位到第3（起始为0）个数据块，这里写错了应该是2*sizeof（e1）
+    out.write((char*)&e5,sizeof(e5));	//将e5写到第3个数据块位置，覆盖e3
+    out.close();			//关闭文件
     system("pause");
-}
+}