char *str1; str1=new char(30);与 char str1[30];有何区别，为何输入还不到20个字母，程序就崩溃了？

#include<iostream>
using namespace std;
class person{
private:
    char *name;
    int number;
public:
    person(char *str,int _number){
        number=_number;
        name=new char[strlen(str)+1];
        strcpy(name,str);
    }
    void show(){ cout<<"姓名："<<name<<endl;
                 cout<<"编号："<<number<<endl;
    }
   
};

class student:public person{
private:
    int classnumber;
    double score;
public:
    student(char*str,int _number,int _classnumber,double _score)
        :person(str,_number){
            classnumber=_classnumber;
            score=_score;
    }
    void show1(){person::show();
                 cout<<"学号："<<classnumber<<endl;
                 cout<<"分数："<<score<<endl;
    }
};

class teacher:public person{
private:
    char *department;
    char *profession;
public:
    teacher(char *str,int _number,char *str1,char *str2):
      person(str,_number){
          department=new char[strlen(str1)+1];
          profession=new char[strlen(str2)+1];
          strcpy(department,str1);
          strcpy(profession,str2);
      }
      void show2(){person::show();
                   cout<<"部门："<<department<<endl;
                   cout<<"职称："<<profession<<endl;
    }
};

void main(){
    char *name;
    name=new char();
    cout<<"请输入学生的姓名：";
    cin>>name;
    int number;
    cout<<"请输入学生的编号：";
    cin>>number;
    int classnumber;
    cout<<"请输入学生的班号：";
    cin>>classnumber;
    double score;
    cout<<"请输入学生的分数：";
    cin>>score;
    cout<<"\n";
    cout<<"学生数据如下:"<<endl;
    student s(name,number,classnumber,score);
    s.show1();
    cout<<"\n";
    char *str;
    str=new char(10);
    cout<<"请输入教师的姓名：";
    cin>>str;
    int number1;
    cout<<"请输入教师的编号：";
    cin>>number1;
//    char *str1;
    char str1[30];
    //str1=new char(30);
    cout<<"请输入教师的部门：";
    cin>>str1;
    char *str2;
    str2=new char(10);
    cout<<"请输入教师的职称：";
    cin>>str2;
    cout<<"\n";
    cout<<"教师的数据如下:"<<endl;
    teacher t(str,number1,str1,str2);
    t.show2();
}