我有以下无法更改的代码
typedef struct
{
char* firstName;
char* lastName;
int id;
float mark;
}* pStudentRecord;
现在我按以下方式分配内存:
g_ppRecords = (pStudentRecord*) malloc (sizeof(pStudentRecord*) *(g_numRecords)); /*allocate required memory for the array of pointers to instances of pStudentRecord*/
/*populate the data structure with records from the text file*/
while (count<g_numRecords)
{
fscanf(g_pf,"%s %s %i %f\n",&fn,&ln,&i,&m);
/*allocate memory for each student record. the pointer to each of these will be stored in the array g_ppRecords*/
g_ppRecords[count]=(pStudentRecord)malloc(sizeof(char*)*2+sizeof(int)+sizeof(float));
/*allocate memory for the firstName and lastName on the heap for each record. use only as much space as is required*/
g_ppRecords[count]->firstName=(char*)malloc(strlen(fn));
g_ppRecords[count]->lastName=(char*)malloc(strlen(ln));
/*assign values stored in local variables to the ones on heap for each record*/
strcpy(g_ppRecords[count]->firstName,fn);
strcpy(g_ppRecords[count]->lastName,ln);
g_ppRecords[count]->id=i;
g_ppRecords[count]->mark=m;
++count; /*onto next record*/
}
但是我无法释放它。这就是我正在做的事情:
while (count<g_numRecords)
{
/*copy variables in the struct instance into local variables*/
strcpy(fn,g_ppRecords[count]->firstName);
strcpy(ln,g_ppRecords[count]->lastName);
id=g_ppRecords[count]->id;
mark=g_ppRecords[count]->mark;
free(g_ppRecords[count]->firstName);
g_ppRecords[count]->firstName=NULL;
free(g_ppRecords[count]->lastName);
g_ppRecords[count]->lastName=NULL;
free(g_ppRecords[count]);
++count;
#ifdef DEBUG
printf("\n%s %s %d %.2f",fn,ln,id,mark);
#endif
/*detect any errors while writing to file*/
if(fprintf(g_pf,"%s %s %d %.2f\n",fn,ln,id,mark) ==-1)
perror("");
else{
#ifdef DEBUG
printf("success");
#endif
}
#ifdef DEBUG
printf("return val=%d",now);
#endif
}
free(g_ppRecords); /*free memory after writing to file is complete*/
g_ppRecords=NULL; /*make pointer point to NULL*/
fclose(g_pf); /*close file stream*/
}
我知道这可能与分配内存有关:
g_ppRecords[count]=(pStudentRecord)malloc(sizeof(char*)*2+sizeof(int)+sizeof(float));
但我无法将其分配为
g_ppRecords[count]=(pStudentRecord)malloc(sizeof(pStudentRecord));
请帮忙!