#include<iostream> #include<string> #include<fstream> using namespace std; class CStudent { public: string m_name; double m_score[3]; double m_aver; CStudent(); bool Setdata(); void Output(); void Aver(); }; CStudent::CStudent() { m_aver = 0; //memset(m_name, 0, 10); } void CStudent::Aver() { m_aver = (m_score[0] + m_score[1] + m_score[2]) / 3; } bool CStudent::Setdata() { return bool(cin >> m_name >> m_score[0] >> m_score[1] >> m_score[2]); //Aver(); //return 0; } void CStudent::Output() { cout << m_name << m_score[0] << m_score[1] << m_score[2] << m_aver << endl; } class CStuFile { CStudent st[100]; CStudent stu; ifstream infile; ofstream outfile; public: int AddTo(); int List(); void Sort(); }; int CStuFile::AddTo() { outfile.open("students.dat", ios::out | ios::binary); if (!outfile) { cout << "open error!" << endl; return 0; } while (stu.Setdata())//cin >> stu.m_name >> stu.m_score[0] >> stu.m_score[1] >> stu.m_score[2] { outfile.write((char *)& stu, sizeof(stu)); } outfile.close(); return 1; } int CStuFile::List() { int p; int i = 0; //CStudent s[10]; infile.open("students.dat", ios::in | ios::binary); if (!infile) { cout << "open error!" << endl; return 0; } while (infile.read((char *) &st[i], sizeof(st[i]))) { //st[i] = stu; cout << st[i].m_name << st[i].m_aver << endl; ++i; } int j = i; infile.close(); outfile.open("students scroe.dat",ios::out|ios::binary); if(!outfile) { cout << "open error!" <<endl; infile.close(); return 0; } for(i = 0; i< j; ++i) { outfile.write( (char * ) & st[i], sizeof(st[i]) ); } outfile.close(); return 1; } int main() { CStuFile sf; sf.AddTo(); sf.List(); return 0; } |
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测试了几次,总在List函数的读操作时程序崩掉,但如果吧read函数的第一个参数换成非数组对象,如stu,运行就没问题。我用的是vs2013,不会是ide的问题吧
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30分 |
把 string m_name;
改成 char m_name[50]; 这样就好了。 string类对象的结构有点复杂,直接这样write/read是不行的。如果一定要用string,那么读写文件的方法和格式就必须改。 |
这是什么原因,同样用string,使用普通对象接收时就可以,但用对象数组里的某一个元素接收时就不行 |
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理解对象模型
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10分 |
string是对象,不是一段内存,不适合直接读写其保存的内容,适合序列化/反序列化。
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