我在波纹管代码中有问题 [英] I have problem in bellow code

问题描述

它表示需要持续表达

3个arraays有什么问题？



我尝试了什么：

it says constant expression required
what is the problem with 3 arraays?

What I have tried:

#include<iostream.h>
#include<conio.h>
int main()
{
    int n,i=0,m=0,unit[n];
    float grade[n];
    char name[n];
    cout<<"How many lessons did you take?";
    cin>>n;
    for(i;i<n;i++)
    {
        cout<<"\n Enter the name of your lesson"<<": \t";
        cin>>name[i];
        cout<<"\n Enter the units"<<": \t";
        cin>>unit[i];
        cout<<"\n Enter the grade"<<": \t";
        cin>>grade[i];
    }
    cout<<"\n your resaults:";
    cout<<"\n Lesson \t"<<"Units \t"<<"\t Grade \n";
    for(m;m<n;m++)
    {
        cout<<name[m]<<"\t"<<unit[m]<<"\t"<<"\t"<<grade[m];
    }

    getch();
    return 0;
}

推荐答案

嘿， C ++ 不是<$ ç$ C> C 。尝试

Hey man, C++ is not C. Try

using namespace std;

struct Lesson
{
  string name;
  int unit;
  double grade;
};

ostream & operator << ( ostream & os, const Lesson & lesson);

istream & getLesson( istream & is, ostream & os, Lesson & lesson);

int main()
{
  size_t n;
  vector <Lesson> vl;
  cout << "how many lessons did you take?\n";
  cin >> n;
  for (size_t l = 0; l<n && cin; ++l)
  {
    Lesson lesson;
    if ( getLesson(cin, cout, lesson) )
      vl.push_back(lesson);
  }

  for (const auto & lesson : vl)
    cout << lesson << "\n";
}

ostream & operator << ( ostream & os, const Lesson & lesson)
{
  os << lesson.name << "\t" << lesson.unit << "\t" << lesson.grade;
  return os;
}

istream & getLesson( istream & is, ostream & os, Lesson & lesson)
{
  os << "enter the name:\t";
  is >> lesson.name;
  os << "enter the unit:\t";
  is >> lesson.unit;
  os << "enter the grade:\t";
  is >> lesson.grade;
  return is;
};

无论您使用什么版本的C ++，都无法声明动态大小的数组 n 在知道 n 之前。

Whatever the version of C++ you use, you can not declare arrays of dynamic size n before knowing n.

int n,i=0,m=0;
cout<<"How many lessons did you take?";
cin>>n;
int unit[n];
float grade[n];
char name[n];

如果这不起作用，则需要查看分配动态数组的语法

if this don't work, you will need to see syntax to allocate dynamic arrays

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