关于 c：如何在结构数组中为 typedef 结构分配内存

How to allocate memory to a typedef struct within array of structs

我一直在尝试为指针变量分配内存，但它一直给我错误或分段错误。如何正确初始化指向课程结构的指针变量？

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typedef struct {
char courseId[7];
char courseName[10];
} Course;

struct Student{
char firstName[10];
char lastName[10];
int studentId;
Course *course;
};

int main() {
int numStudents;
printf(“How many students do you wish to register?:”);
scanf(“%d”, &numStudents);
struct Student *student[numStudents];
student[numStudents] = malloc(sizeof(*student[numStudents]));
student[numStudents]->course = malloc(sizeof*(numStudents * Course));
for (int i = 0; i < numStudents; i++) {
printf(“Enter student #%d First Name:”, i+1);
scanf(“%s”, student[i]->firstName);
printf(“Enter student Last Name:”);
scanf(“%s”, student[i]->lastName);
printf(“Enter Student ID:”);
scanf(“%d”, &student[i]->studentId);
printf(“Enter Course ID:”);
//student[i]->course = malloc(sizeof(*(student[i]->course)));
scanf(“%s”, student[i]->course->courseId);
printf(“Enter Cousrse Name:”);
//student[i]->course = malloc(sizeof(*(student[i]->course)));
scanf(“%s”, student[i]->course->courseName);
}

for (int i = 0; i < numStudents; i++) {
printf(“Student Name: %s %s\
“, student[i]->firstName, student[i]->lastName);
printf(“Student ID: %d\
“, student[i]->studentId);
printf(“Course Code: %s\
“, student[i]->course->courseId );
printf(“Course name: %s\
“, student[i]->course->courseName);
free(student[i]->course);
}

相关讨论

避免无宽度 scanf(“%s”, student[i]->firstName); 字符串输入。最好使用 char firstName[10]; …. scanf(“%9s”, student[i]->firstName);

您几乎完成了，需要进行一些更正。
Student 中的课程对象不需要是指针。 Student 结构的数组需要动态分配，然后再释放。 -> 用作取消引用运算符，但在您的情况下， [] 已经取消引用，因此您将使用 . 而不是 -> 并且当您为结构数组分配内存时，它需要是结构的大小乘以结构的数量。 malloc(sizeof(struct Student)*numStudents);

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typedef struct {
char courseId[7];
char courseName[10];
} Course;

struct Student{
char firstName[10];
char lastName[10];
int studentId;
Course course;
};

int main() {
int numStudents;
printf(“How many students do you wish to register?:”);
scanf(“%d”, &numStudents);
struct Student* students = malloc(sizeof(struct Student)*numStudents);
for (int i = 0; i < numStudents; i++) {
printf(“Enter student #%d First Name:”, i+1);
scanf(“%s”, students[i].firstName);
printf(“Enter student Last Name:”);
scanf(“%s”, students[i].lastName);
printf(“Enter Student ID:”);
scanf(“%d”, &students[i].studentId);
printf(“Enter Course ID:”);
scanf(“%s”, students[i].course.courseId);
printf(“Enter Cousrse Name:”);
scanf(“%s”, students[i].course.courseName);
}

for (int i = 0; i < numStudents; i++) {
printf(“Student Name: %s %s\
“, students[i].firstName, students[i].lastName);
printf(“Student ID: %d\
“, students[i].studentId);
printf(“Course Code: %s\
“, students[i].course.courseId );
printf(“Course name: %s\
“, students[i].course.courseName);
}
free(students);
return 0;
}

我试图对您的代码进行最小的更改。

How to allocate memory to a typedef struct within array of structs

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