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Update 12-9.cpp

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Falling-in-W-sweetty
2022-08-14 11:25:49 +08:00
committed by GitHub
parent 9f58fef2ce
commit 4b0ba90862
1 changed files with 12 additions and 12 deletions
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24
practical_exercises/10_day_practice/day10/文件例题/12-9.cpp
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@@ -22,20 +22,20 @@ public:
}; };
int main(){ int main(){
ofstream out("D:/Employee.dat",ios::out); //<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ļ<EFBFBD> ofstream out("D:/Employee.dat",ios::out); //定义随机输出文件
Employee e1(1,"<EFBFBD><EFBFBD><EFBFBD><EFBFBD>",23,2320); Employee e1(1,"张三",23,2320);
Employee e2(2,"<EFBFBD><EFBFBD><EFBFBD><EFBFBD>",32,3210); Employee e2(2,"李四",32,3210);
Employee e3(3,"<EFBFBD><EFBFBD><EFBFBD><EFBFBD>",34,2220); Employee e3(3,"王五",34,2220);
Employee e4(4,"<EFBFBD><EFBFBD><EFBFBD><EFBFBD>",27,1220); Employee e4(4,"刘六",27,1220);
out.write((char*)&e1,sizeof(e1)); //<EFBFBD><EFBFBD>e1,e2,e3,e4˳<EFBFBD><EFBFBD>д<EFBFBD><EFBFBD><EFBFBD>ļ<EFBFBD> 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*)&e2,sizeof(e2));
out.write((char*)&e3,sizeof(e3)); out.write((char*)&e3,sizeof(e3));
out.write((char*)&e4,sizeof(e4)); out.write((char*)&e4,sizeof(e4));
//<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĵ<EFBFBD><EFBFBD>뽫e3<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>壩<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ40<EFBFBD><EFBFBD> //下面的代码将e3（即王五）的年龄改为40岁
Employee e5(3,"<EFBFBD><EFBFBD><EFBFBD><EFBFBD>",40,2220); Employee e5(3,"王五",40,2220);
out.seekp(3*sizeof(e1)); //ָ<EFBFBD>붨λ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>3<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʼΪ0<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݿ<EFBFBD> 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)); //<EFBFBD><EFBFBD>e5д<EFBFBD><EFBFBD><EFBFBD><EFBFBD>3<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݿ<EFBFBD>λ<EFBFBD>ã<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>e3 out.write((char*)&e5,sizeof(e5)); //将e5写到第3个数据块位置，覆盖e3
out.close(); //<EFBFBD>ر<EFBFBD><EFBFBD>ļ<EFBFBD> out.close(); //关闭文件
system("pause"); system("pause");
} }