How to scan multiple strings in one place? [closed]

Question

I am working on a project. I need to get each student's courses and their number, for example:

Lisa Miller  890238
Mathematics  MTH345
Physics  PHY357  
ComputerSci  CSC478  
History  HIS356  

I do not know how to register all those courses and their numbers in one place specified for that student. What should I do?

Answer 1

It looks like you need two structures:

One for the student and their list of courses, and one for a course.

Assuming you know maximum number of courses a student can take:

struct course {
    char name[MAX_COURSE_NAME_LEN];
    char id[MAX_COURSE_ID_LEN]; //this one should be 7
};

struct student {
    char name[MAX_STUDENT_NAME_LEN];
    unsigned int id; //student ids are all numbers, right?
    int num_courses; //number of courses student actually takes
    struct course courses[MAX_COURSES];
}

If you want to be memory efficient or the maximum number of courses a student can take is not specified, you should used a linked list of courses instead of an array.

You will need custom code to read this from file and write it back to a file.

C standard library does not come with serialization and deserialization functions, but if this is more than a homework project, you may want to look for a dedicated serialization library.

Answer 2

Here are steps you can follow:

• define a structure for student courses with these fields:
  • a pointer to the next student course
  • a pointer to the course name
  • a string for the course ID
• define a structure for the student with these fields:
  • a pointer to the next student
  • a string pointer for their name
  • an integer for their student ID
  • a pointer to a list of courses
• define a pointer to a list of students, initialized to NULL
• in a loop: read the file one line at time
  • trim trailing spaces
  • locate the last word
  • if it starts with a digit:
    • allocate a new student structure and link it at the end of the student list.
    • convert the number as the student number using strtoul()
    • copy the beginning of the line as the student name using strdup()
  • otherwise the line is a course:
    • allocate a new student course and link it at the end of the current student's course list
    • copy the word as the course ID using sscanf()
    • copy the beginning of the line as the course name using strdup()

Constraints:

• do not use strtok()
• do not use strcpy()
• prevent all buffer overflows
• detect malformed input and output a meaningful error message

You can write a printing routine to print the complete student list and compare the output with the file contents for validation.