为什么我不能在结构的对象数组中插入值？ [英] Why can't I insert values in an array of objects of a structure?

问题描述

我有这段代码，-collection-是我的fstream对象，-students-是我制作的结构。我创建了-file [ctr] - 这是一个学生对象的数组，当我构建并运行它时，我使用的IDE是Code :: Blocks不会给我错误。错误消息[fileprocessing.exe已停止工作。填写名字后出现问题导致程序停止正常工作......等。知道我的代码可能有什么问题吗？

I have this block of code, -collection- is my fstream object and -students- is a structure I made. I made -file[ctr]- which is an array of objects of students, when I build and run it, the IDE I use which is Code::Blocks don't give me errors. The error message [fileprocessing.exe has stopped working. A problem caused the program to stop working correctly...etc.] appears after I fill up firstname. Any idea to what may be wrong with my code?

if(choice2=='A'||choice2=='a'){
    students file[ctr];
    cout<<"Student ID: ";
    cin>>file[ctr].studentID;
    cout<<"Surname: ";
    cin>>file[ctr].surname;
    cout<<"Firstname: ";
    cin>>file[ctr].firstname;
    cout<<"Birthdate: ";
    cin>>file[ctr].birthdate;
    cout<<"Sex: ";
    cin>>file[ctr].sex;
    fstream collection(filename, std::fstream::in | std::fstream::out | std::fstream::app);
    collection<<ctr
    <<"\t"<<file[ctr].studentID
    <<"\t"<<file[ctr].surname
    <<"\t"<<file[ctr].firstname
    <<"\t"<<file[ctr].birthdate
    <<"\t"<<file[ctr].sex
    <<endl;
    collection.close();
    ctr++;
    system("cls");
}

我的尝试：

What I have tried:

int ctr=1;
if(choice2=='A'||choice2=='a'){
    students file;
    cout<<"Student ID: ";
    cin>>file.studentID;
    cout<<"Surname: ";
    cin>>file.surname;
    cout<<"Firstname: ";
    cin>>file.firstname;
    cout<<"Birthdate: ";
    cin>>file.birthdate;
    cout<<"Sex: ";
    cin>>file.sex;
    fstream collection(filename, std::fstream::in | std::fstream::out | std::fstream::app);
    collection<<ctr<<"\t"<<file.studentID
                        <<"\t"<<file.surname
                        <<"\t"<<file.firstname
                        <<"\t"<<file.birthdate
                        <<"\t"<<file.sex
                        <<endl;
    collection.close();
    ctr++;
    system("cls");
}

简单，我刚删除了[ctr]并且效果很好，但我知道这会导致当我在系统的其他部分工作时，我遇到了问题。我必须创建一个对象数组，因为我在一组文本文件中有一组学生数据，它们不应该是学生对象...请帮助！

Simple, I just removed the [ctr]s and it works well, but I know it's going to cause me problems when I work on the other parts of my system. I have to make an array of objects because I have a collection of student data in a collection of text files and they shouldn't be of a students object... Please help!

推荐答案

students file[ctr];
cout<<"Student ID: ";
cin>>file[ctr].studentID;

这是错的;你正在声明一个学生对象的数组，并立即使用count作为数组的索引（有效数组索引从0到count - 1）。因此，在这种情况下，它意味着您创建的结构将覆盖您的内存并最终导致一些随机事件，例如应用程序崩溃。你应该这样做：

That is wrong; you are declaring an array of students objects, and immediately using the count as an index into the array (valid array indices go from 0 to count - 1). So in this case it means that the structure you create will be overwriting your memory and ultimately cause some random event, such as an application crash. You should do it like:

int count; // the number of elements in the array
// initialise count somehow

// declare the array of 'count' elements
students file[count];

// now use a loop to fill the array
int ctr;
for (ctr = 0; ctr < count; ++ctr)
{
    cout<<"Student ID: ";
    cin>>file[ctr].studentID;
// ... etc
} // end of for loop

这篇关于为什么我不能在结构的对象数组中插入值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！