Question

所以我一直在练习链接列表，我编写了一个可以完美运行的代码，然后又编写了另一个与我的第一个代码几乎相同但目标不同的代码，问题是当我运行第二个代码时循环然后停止。（问题实际上是使用了malloc）

这是我的第一个代码：

#include <iostream>
#include <stdio.h>
#include <cstdlib>
#include <iomanip>
struct student
{
    string name;
    int age;
    double grade;
    student *next;
};

student *head;


void createList(int n)
{
    student *newNode,*temp;
    int i;
    string name_temp;
    int age_temp;
    double grade_temp;

    head=(student *) malloc(sizeof(student));

    if(head==NULL)
    {
        cout<<("Unable to alocate memory");


    }
    cout<<"Enter student's initials: ";
    cin>>name_temp;
    cout<<"Enter student's age: ";
    cin>>age_temp;
    cout<<"Enter Student's grade";
    cin>>grade_temp;


    head->name=name_temp;
    head->age=age_temp;
    head->grade=grade_temp;
    head->next=NULL;

    temp=head;
    for(i=2;i<=n;i++)
    {
        newNode=(student *)malloc(sizeof(student));
        if(newNode==NULL)
        {
            cout<<"unable to allocate memory";
            break;
        }
        cout<<"Enter the data of node "<<i<<":\n";
        cout<<"Enter student's initials: ";
        cin>>name_temp;
        cout<<"Enter student's age: ";
        cin>>age_temp;
        cout<<"Enter Student's grade";
        cin>>grade_temp;

        newNode->name=name_temp;
        newNode->age=age_temp;
        newNode->grade=grade_temp;
        newNode->next=NULL;
        temp->next=newNode;
        temp=temp->next;

    }


}
void traverseList()
{
    student *cond;
    if(head==NULL)
    {
        cout<<"List is empty";
        return;
    }
    cond=head;
    cout<<"NAME:\t\t\tAGE:\t\tGRADE:\n";
    while(cond!=NULL)
    {
        cout<<cond->name<<"\t\t\t"<<cond->age<<"\t\t"<<fixed<<setprecision(2)<<cond->grade<<endl;
        cond=cond->next;

    }
}
int main() {

    int n;

    cout <<"Enter the total Number of Student Record: ";
    cin>>n;
    createList(n);
    cout<<"\nData in the list\n";
    traverseList();
    return 0;
}

这是我的第二个代码：

#include <iostream>
#include <stdio.h>
#include <cstdlib>
#include <iomanip>
struct staff
{
    string name,pos;
    double sal;
    staff *next;

};
staff *admin;
void createList(int n)
{
    staff *nodes,*temp;
    int i;
    string name_temp;
    string pos_temp;
    double sal_temp;
    admin=(staff *)malloc(sizeof(staff));//
    if(admin==NULL)
    {
        cout<<"unable to allocate memory";
    }
    cout<<"Enter Employee's name: ";
    cin>>name_temp;
    cout<<"Enter Employee's Position: ";
    cin>>pos_temp;
    cout<<"Enter Employee's Salary: ";
    cin>>sal_temp;

    admin->name=name_temp;
    admin->pos=pos_temp;
    admin->sal=sal_temp;
    admin->next=NULL;

    temp=admin;

    for(i=2;i<=n;i++)
        {

            nodes=(staff*)malloc(sizeof(staff));
            if(nodes==NULL)
                {
                    cout<<"Unable to allocate memory";

                }
            cout<<"Enter the data of node "<<i<<":\n";
            cout<<"Enter Employee's name: ";
            cin>>name_temp;
            cout<<"Enter Employee's Position: ";
            cin>>pos_temp;
            cout<<"Enter Employee's Salary: ";
            cin>>sal_temp;

            nodes->name=name_temp;
            nodes->pos=pos_temp;
            nodes->sal=sal_temp;
            nodes->next=NULL;
            temp->next=nodes;
            temp=temp->next;

        }
}
void viewList()
{
    double total=0;
    staff *check;
    if(admin==NULL)
        {
            cout<<"No list";
        }
    check=admin;
    cout<<"NAME:\t\tPosition\t\tSalary\n";
    while(check!=NULL)
    {
        cout<<check->name<<"\t\t"<<check->pos<<"\t\t"<<fixed<<setprecision(2)<<check->sal<<endl;
        total=total+check->sal;
        cout<<check->name<<"\t\t\t\ttotal: "<<total<<endl;
        check=check->next;
    }

}

int main()
{
    int n;
    cout<<"Enter Number of employees: ";
    cin>>n;
    createList(n);
    cout<<"\nin the list is\n";
    viewList();
    return 0;
}

链表未循环<完成>

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