Thread: Need help with Searching within Structs

Hello! I am looking for help with the below code. This is for a class and I would like help figuring out how to complete the missing code. I don't want someone to finish it for me because I won't learn anything. I missed 2 weeks of class due to a death in the family and family illnesses, so I really need to learn how to write this.

I have to complete two remaining sections of the code below. I'm not sure what to write in the YOUR CODE GOES HERE parts. First part is a lookup function. The second is adding them to an array. I've tried googling, but just end up getting more and more confused.

This is my first coding course, so any and all help is appreciated!

Code:

#include "stdio.h"
#include "stdlib.h"

typedef unsigned int uint;

struct Student
{
  // add the definition of the struct
  char name[30];
  uint id;
  char department;
  char course;
  uint admit_year;
};

/* This function accepts an array of struct Student structs and an integer
cohort_year and returns an array of students with a admit_year that matches.*/
void cohort_finder(struct Student *, uint, uint);

void student_lookup(struct Student *, uint, uint);

void print_student_record(struct Student);

int main(int argc, char const *argv[]) {

  struct Student student_roster[100];

  struct Student s;

  s.name = "Test Student";
  s.department = "Engineering";
  s.course = "N/A";
  s.admit_year = 2009;
  s.id = 0001;

  student_roster[0] = s;

  printf("Performing Cohort Finder for Year: 2009\n");
  cohort_finder(student_roster,1, 2009);

  printf("Performing Student Lookup for id: 0001\n");
  student_lookup(student_roster, 1, 0001);

  return 0;
}

void student_lookup(struct Student students[], uint n, uint id)
{
  struct Student matching_student;

  /* YOUR CODE GOES HERE!
    Complete the student ID lookup function such that it prints the matching
    student's record. The printing code already exists.
  */


  printf("Matching Student Is:\n");
  print_student_record(matching_student);
}

void cohort_finder(struct Student students[], uint n, uint cohort_year)
{

 // create an oversized array on the heap to contain the matching students
  struct Student * cohort_students = (struct Student*)malloc(sizeof(struct Student)*n);

 // j is the counter for the matching students
  uint j = 0;

  /* YOUR CODE GOES HERE!
    Your code should find the matching students in the struct Student array and
    add them to a new array (cohort_students).
  */
  for (j = 0; j < 5; j++){ /*I did this part but got confused about what to put next. 
If I'm not mistaken, this should advance j through the array, correct?
Not sure how to add to the array here*/

    
  }

  // resize the heap allocation so the size can be determined using sizeof
  cohort_students = (struct Student*)realloc(cohort_students, j*sizeof(struct Student));

  // check if the pointer is null
  if(cohort_students == NULL)
  {
    printf("Something Went Wrong During Allocation of cohort_students\n");
  }

  printf("The Students from %d Are:\n", cohort_year);
  for(uint i=0; i<j; i++)
  {
    print_student_record(cohort_students[i]);
  }
}

void print_student_record(struct Student student)
{
  printf("\n");
  printf("Student Name: %s\n", student.name);
  printf("Student department: %s\n", student.department);
  printf("Student course: %s\n", student.course);
  printf("Student admit year: %d\n", student.admit_year);
  printf("Student id: %d\n", student.id);
  printf("\n");
}

Originally Posted by Salem

> void cohort_finder(struct Student *, uint, uint);
You can have names along with the types in a prototype.
So you have less to describe when describing the interface.

Code:

void cohort_finder(struct Student students[], uint n, uint cohort_year);

> s.name = "Test Student";
You can't assign an array, you have to use strcpy.

> s.department = "Engineering";
> s.course = "N/A";
You can't assign a string to a single char.
Were these fields meant to be arrays?

> s.id = 0001;
Be aware that numbers beginning with 0 are interpreted as octal (base 8) numbers.
Fine for the moment, but not so good when you've counted your way up to 0008.

> Complete the student ID lookup function such that it prints the matching
for ( uint i = 0 ; i < n ; i++ ) // loop over all students
if ( students[i].id == id // test for a match against a field within the struct
I'm sure you can figure the rest out.


> struct Student * cohort_students = (struct Student*)malloc(sizeof(struct Student)*n);
You don't need the cast in a C program.
struct Student * cohort_students = malloc(sizeof(struct Student)*n);
If you get a message about not being able to convert void*, then you're compiling your C program with a C++ compiler. Use a C compiler.

> Your code should find the matching students in the struct Student array and
It's the same basic loop used above.

The only other line of code you need is this, when you've found a cohort member.
cohort_students[j] = students[i];

Thank you so much! It turns out that the code provided for us to complete had some errors, which you identified. So there was much more to this than just inserting missing code, we had to fix the original code! (correcting the code was not in the assignment instructions. lol.) I had to look up "strcpy" as we hadn't covered that yet in class, but wouldn't compile without it. So thank you for your help and explanations!