你能解释一下这个错误背后的原因吗？
错误代码：
在需要标量的情况下使用了结构类型值
for(;*ptr;ptr++)“以下代码？
为什么我们不允许在 for 循环中使用结构变量？
#include<stdio.h>
#include<stdlib.h>
struct student
{
char name[20]; // Given
int math; // Marks in math (Given)
int phy; // Marks in Physics (Given)
int che; // Marks in Chemistry (Given)
int total; // Total marks (To be filled)
int rank; // Rank of student (To be filled)
};
static int count=1;
void enter_data(struct student* arr,int num);
void print_data(struct student* arr,int num);
int main()
{
int num=1;
char ch;
printf("Enter the number of student records you want to input?..\n");
scanf("%d",&num);
struct student *arr=(struct student*)malloc(num*sizeof(struct student));
printf("Do you want to enter the student record...(Y/N)\n");
scanf(" %c",&ch);
if(ch=='y'||ch=='Y')
{
enter_data(arr,num);
printf("The created record is .....\n");
print_data(arr,num);
}
else
return 0;
}
void enter_data(struct student* arr,int num)
{
int i;
struct student* ptr=arr;
for(;count<=num;ptr++,count++)
{
printf("Enter the name of the candidate...\n");
scanf("%s",ptr->name);
printf("Enter the marks scored in maths,phy,che....\n");
scanf("%d%d%d",&ptr->math,&ptr->phy,&ptr->che);
((ptr->total)=(ptr->math)+(ptr->phy)+(ptr->che));
}
}
void print_data(struct student* arr,int num)
{
int i;
struct student* ptr=arr;
for(;*ptr!=NULL;ptr++)//error here
{
printf("Name of the candidate...%s\n",ptr->name);
printf("Enter the marks scored in maths...%d\t physics... %d\tche... %d\n total=%d\n",ptr->math,ptr->phy,ptr->che,ptr->total);
}
}