C - 构建动态分配的指针数组，指向填充了文件输入的结构(C - Build dynamically allocated array of pointers to structures filled with input from file)

 我需要构建一个指向动态分配结构（DBrecord）的指针数组，并用另一个文件的输入填充该数组。 不知道如何处理这个问题。 
 
 数据文件将首先具有条目数，然后是特定顺序的条目。 
 
 numOfEntries 
 
 lastName firstName studentID year gpa expGradYear 
 
 例： 
 
 1 
 
 Doe John 12345678 senior 3.14159 2015 
 
 这是我到目前为止的代码： 
 
 class.h 
 
typedef enum {firstYear, sophomore, junior, senior, grad} class;
 
 main.c中 
 
#include <stdio.h>
#include <stdlib.h>
#include "class.h"

int main(){

//DBrecord is name for structure
struct DBrecord{
int DBrecordID;     //ID for each entry, range 0-319
char *last;         //student last name
char *first;        //student first name
char studentID[8];  //student ID
int age;            //student age
class year;         //year in school
float gpa;          //GPA
int expGradYear;    //expected graduation year
};
int numEntries;     //total number of entries, first num in data file
struct DBrecord **ptrToDB;

//scan first int in data file and assign to numEntries
scanf("%d", &numEntries);

//allocate memory for structures, each is 36 bytes
*ptrToDB = malloc (sizeof(struct DBrecord) * numEntries);

//free allocated memory
free(ptrToDB);

//build an array of pointers to dynamically allocated structures
//fill that array with input from data file

//build 7 arrays of pointers to DBrecords, one for each field except DB ID
//sort each a different way
//note the 7 arrays are pointers, no copying

//print each of the 7 sorted arrays

return 0;
}

I need to build an array of pointers to dynamically allocated structures (DBrecord) and fill that array with input from another file. Not sure how to approach this.
 
The data file will have the number of entries first, followed by entries in a specific order.
 
numOfEntries
 
lastName firstName studentID year gpa expGradYear
 
example:
 
1
 
Doe John 12345678 senior 3.14159 2015
 
Here's the code I have so far:
 
class.h
 
typedef enum {firstYear, sophomore, junior, senior, grad} class;
 
main.c
 
#include <stdio.h>
#include <stdlib.h>
#include "class.h"

int main(){

//DBrecord is name for structure
struct DBrecord{
int DBrecordID;     //ID for each entry, range 0-319
char *last;         //student last name
char *first;        //student first name
char studentID[8];  //student ID
int age;            //student age
class year;         //year in school
float gpa;          //GPA
int expGradYear;    //expected graduation year
};
int numEntries;     //total number of entries, first num in data file
struct DBrecord **ptrToDB;

//scan first int in data file and assign to numEntries
scanf("%d", &numEntries);

//allocate memory for structures, each is 36 bytes
*ptrToDB = malloc (sizeof(struct DBrecord) * numEntries);

//free allocated memory
free(ptrToDB);

//build an array of pointers to dynamically allocated structures
//fill that array with input from data file

//build 7 arrays of pointers to DBrecords, one for each field except DB ID
//sort each a different way
//note the 7 arrays are pointers, no copying

//print each of the 7 sorted arrays

return 0;
}

原文：https://stackoverflow.com/questions/10076261