Question

此代码有什么问题？我正在尝试写一个二进制文件MCQ类型的问题例如，问题：如果计算机向其他人提供数据库服务，那么它将被称为？ 1.Web服务器2.Application 3.Database服务器4.FTP服务器

ID：1

答案：3

但是我得到了不寻常的输出。请查看我提供评论的代码。程序会询问问题并将其写入二进制文件。 id自动递增，向用户询问问题和答案。如果问题是＆＃34; x＆＃34;然后程序停止，如果它的任何其他东西它要求答案并设置所有三个id，问题，回答临时对象，然后将其写入文件。

该程序适用于第一个问题＆amp;回答然后直接询问第二个答案的答案而不要求第二个问题。

#include <iostream>
#include <fstream>
#include<string.h>
#include<conio.h>


using namespace std;

class questions{    //start of class
                    //private members
int id; //identification number for question ( 1,2,3,....)
char ques[100]; //question
int ans;    //answer (1,2,3,4) MCQ
public: //public members

void displayques() //displays question
{
    cout<<ques; //the same
}
int getans()    //returns answer
{
    return ans; //the same

}

int getid() //returns id
{
    return id; //the same
}

void setques(char q[]) //set the given string in parameter to the question.
{
strcpy(ques,q);
}

void setid(int i) //set the given int as id
{
id=i;
}
void setans(int a) //set the given int as answer
{
ans=a;
}
};          //end of class questions

int main()  //start of main
{
    questions quesobj;  //create an object of class questions
ofstream quesfile;  //creates and object of class ofstream

quesfile.open("questions.dat",ios::out|ios::binary);    //opens questions.dar in output mode as binary with the object quesfile of ofstream


char ask='y';   //to stop the process when its changed to n
char tempques[100]; //to temporarily store the question
int tempid=1;   //to temporarily store the id, initially at 1, later is incremented
int tempans;    //to temporarily store the answer

while(ask!='n') //runs upto the the point when use wants to escape the loop
{


    cout<<"Question? or enter x to stop"<<endl; //asks the questions also ask if user want to escape can enter x
    gets(tempques); //gets the question in temporary variable
    cout<<"Question registered"<<endl;  //shows question is ready to be written
    if(strcmp(tempques,"x")==0)      //if user enter the question as x
    {
        ask='n'; //sets ask to n which will end the loop
    }
    else        //if user enters something else than x, it is considered the question
    {
            cout<<"Answer:"<<endl;  //ask for the answer
            cin>>tempans;   //stores answer in temporary variable
            cout<<"Answer registered"<<endl; //shows answer is ready to be written
            quesobj.setid(tempid);  //sets id to the temp object of the class questions
            quesobj.setques(tempques); //sets question to the temp object of the class questions
            quesobj.setans(tempans); //sets answer to the temp object of the class questions

       quesfile.write((char *)&quesobj, sizeof(quesobj));   //write the temp object of class questions to the binary file
       tempid++;   //tempid is incremented for the next loop so that every question has its own id

    }



} //end of while
quesfile.close();   // closes the file using the object of ofstream
}

输出：

Question? or enter x to stop
This is my first question?
Question registered
Answer:
2
Answer registered
Question? or enter x to stop
Question registered
Answer:
_

Answer 1

正如评论中所建议的那样，

你不应该混合使用 C和C ++ 样式IO 由于您的代码不是#include <iostream> #include <sstream> #include <fstream> #include <string> using namespace std; int string_to_int(const string& str) { stringstream ss(str); int str_int; ss >> str_int; return str_int; } class Question { int id; string question_string; int answer; public: void displayQuestion() { cout << question_string; } int getAnswer() { return answer; } int getId() { return id; } void setQuestion ( const string& question_string_) { question_string = question_string_; } void setId ( int id_ ) { id = id_; } void setAnswer ( int answer_ ) { answer = answer_; } }; int main() { Question question; ofstream question_file; question_file.open ( "questions.dat", ios::out | ios::binary ); char option = 'y'; string temp_question; int temp_id =1; int temp_answer; while ( option != 'n' ) { cout << "Question? or enter 'x' to stop" << endl; getline(cin, temp_question); cout << "Question registered" << endl; if (temp_question == "x") { option = 'n'; } else { cout << "Answer? :" << endl; string temp_answer_string; getline(cin, temp_answer_string); temp_answer = string_to_int(temp_answer_string); cout << "Answer registered" << endl; question.setId ( temp_id ); question.setQuestion ( temp_question ); question.setAnswer ( temp_answer ); question_file.write ( ( char* ) &question, sizeof ( question ) ); temp_id++; } } question_file.close(); }，我已经清理了一些代码。我测试了它，它现在工作得很好。

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在简单的文件处理程序中获得异常输出

1 个答案: