c++ - 变量的值无法存储

Question

编译器说这段代码没有错误，但是当我输入student total时，不会存储jlh的值，并且不会循环jlh次。我应该如何更改代码？

using std::string;

int main(){
 int jlh,x,y;
 string abs;

 char **mhs=new char*[100];
    
     cout<<"enter students total: ";
     cin>>jlh;
       
     for(x=0;x<jlh;x++){     
     cout<<"enter students name: ";
        cin>>mhs[x];
        cout<<"enter students presensi: ";
        cin>>abs[x];
        cout<<endl;
      }
      
 
  getch();
  }

Answer 1

在阅读之前，您必须分配位置来存储阅读的内容:

#include <iostream>
#include <string>
using std::cin;
using std::cout;
using std::endl;
using std::string;

int main(){
    int jlh,x,y;
    string abs;

    char **mhs=new char*[100];

    cout<<"enter students total: ";
    cin>>jlh;

    abs.resize(jlh); // allocate for presensi
    for(x=0;x<jlh;x++){
        cout<<"enter students name: ";
        mhs[x] = new char[1024000]; // allocate for name, hoping this is enough...
        cin>>mhs[x];
        cout<<"enter students presensi: ";
        cin>>abs[x];
        cout<<endl;
    }
}

使用 std::vector和 std::string代替原始数组应该更好:

#include <iostream>
#include <string>
#include <vector>
using std::cin;
using std::cout;
using std::endl;
using std::string;

int main(){
    int jlh,x,y;

    cout<<"enter students total: ";
    cin>>jlh;

    // allocate jlh elements for each vectors
    std::vector<string> mhs(jlh);
    std::vector<char> abs(jlh);

    for(x=0;x<jlh;x++){
        cout<<"enter students name: ";
        cin>>mhs[x];
        cout<<"enter students presensi: ";
        cin>>abs[x];
        cout<<endl;
    }
}