使用fscanf将文件中的元素读入链接列表

Question

我在循环中使用fscanf读取值到链接列表时遇到麻烦。

该程序最终会编译并运行，但是print函数未产生任何输出，这使我相信在我的read函数中实际上并未创建我的链表。

我设置了一些错误检查printf语句，并发现我的学生* head值返回到main然后发送到print函数时为NULL。

我的职能：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct Student{
    char* first;
    char* last;
    int i;
    int j;
    struct Student* next;
}student;

int main(int argc, char* argv[])
{
    student *start = NULL;
    char *studentInput = argv[1];
    start = buildStudentList(studentInput,start);
    printStudents(start);
    free_students(start);
    return 0;
}

student* buildList(char* studentsFile, student* head) 
{
    student *current = head;
    char *f = malloc(sizeof(char) * 25);
    char *l = malloc(sizeof(char) * 25);
    int prior,level = 0;
    FILE *in = fopen(studentsFile, "r");

    if(in == NULL)
    {
        printf("\nThe input file failed to open\n");
        return NULL;
    }
    else
    {
        while(!feof(in))
        {
            fscanf(in, "%s %s %d %d",f,l,&prior,&level);
            student *new = (student*)malloc(sizeof(student));
            new->first = (char*)malloc(sizeof(char) * 25);
            new->last = (char*)malloc(sizeof(char) * 25);
            current = new;
            strcpy(current->first,f);
            strcpy(current->last,l);
            current->i = prior;
            current->j = level;
            current->next = NULL;
            current = current->next;
        }
        free(first);
        free(last);
        fclose(in);
        return head;
    }
}

void print(student* head) 
{
    if(head == NULL)
    {
        printf("head is null");
        return;
    }

    student *current = head;

    while(current->next != NULL)
    {
        printf("\n\nFirst Name: %s\nLast Name: %s\nPriority: %d\nReading Level: %d\n\n", current->first, current->last, current->i, current->j);
        current = current->next;
        printf("makes to loop");
    }
}

void free_students(student *head)
{
    if(head == NULL)
    {
        return;
    }

    student *current = head;
    while(current->next != NULL)
    {
        student *temp = current;
        current = current->next;
        free(temp->first);
        free(temp->last);
        free(temp);
    }
    free(current->first);
    free(current->last);
    free(current);
}

此时，输出为“ head为null”。