Function being called but is not doing anything

I am creating a student management system in C using linked list. I have created a function called search which has takes input from user from one of four options and then performs search operation on the student list.

struct Program { //structure to hold information of program
char p_name[50];    //name of program
char p_code[10];    //code of program
char responsible[50];   //person responsible for program
char r_email[50];   //email of responsible
struct Program *next;
};
struct Student {    //structure to hold information of student
int personal_no;
char name[50];
char gender[6];
struct Program *study_program;
int age;
char email[50];
struct Student *next;
};

The code is not optimized and I will work on making in better but here is the function:

void studyProgram(struct Student *head) {
struct Student *t = NULL;
struct Program *temp = programs;
while (temp != NULL) {
int count = 0;
int male = 0;
int female = 0;
float age = 0;
printf("Program: %s\n", temp->p_name);
t = head;
while (t != NULL) {
if (!strcmp(temp->p_code, t->study_program->p_code)) {
count++;
age += t->age;
if (!strcmp(_strupr(t->gender), "MALE")) {
male++;
} else {
female++;
}
}
t = t->next;
}
age = age / count;
printf("Number of Students: %d\n", count);
printf("Number of Males: %d\n", male);
printf("Number of Females: %d\n", female);
printf("Average age: %f\n", age);
temp = temp->next;
}
}
void search(struct Student *head) {
int p;
struct Student *temp = head;
int ch;
printf("What do you want to search for:\n");
printf("1.Personal Number\n2.Name\n3.Study Program\n4.Statistics\nOption: ");
scanf("%d", &ch);
if (ch == 1) {
printf("Enter personal number:\n");
scanf("%n", &p);
while (temp != NULL) {
if (temp->personal_no == p) {
display(temp);
return;
}
temp = temp->next;
}
}
else if (ch == 2) {
char n[50];
printf("Enter name:\n");
scanf("%s", n);
while (temp != NULL) {
if (!strcmp(temp->name, n)) {
display(temp);
return;
}
temp = temp->next;
}
}
else if (ch == 3) {
char n[10];
printf("Enter program code:\n");
scanf("%s", n);
while (temp != NULL) {
if (!strcmp(temp->study_program->p_code, n)) {
display(temp);
}
temp = temp->next;
}
}
else if (ch == 4) {
int count = 0;
int male = 0;
int female = 0;
float age = 0;
while (temp != NULL) {
count++;
age += temp->age;
if (!strcmp(strupr(temp->gender), "MALE")) {
male++;
} else {
female++;
}
temp = temp->next;
}
age = age / count;
printf("Number of Students: %d\n", count);
printf("Number of Males: %d\n", male);
printf("Number of Females: %d\n", female);
printf("Average age: %f\n", age);
studyProgram(head);
}
}
void display(struct Student *head) {
struct Student *temp = head;
while (temp != NULL) {
printf("Peronsal No: %d\n", temp->personal_no);
printf("Name: %s\n", temp->name);
printf("Gender %s\n", temp->gender);
printf("Study Program: %n\n", temp->study_program->p_name);
printf("Age: %d\n", temp->age);
printf("Email: %s\n", temp->email);
temp = temp->next;
}
}

Option 1-3 perform basic search operation which are self explanatory. Option 4 provides information about, firstly, the total no of players, no of males and females and then their average age. The studyProgram function is then called which calculates the same attributes for each study program.

programs is a global variable structure that contains all the information of the programs (CS, AI).

I have been stuck on this for a long time and cannot figure out a solution.
The studyProgram function is not working at all. The display function is not displaying any information. In case 1, for personal number the input is skipped when the option is selected.

Can anybody point out where I am making a mistake(s)?

programs is a global variable that contains all the information of the programs (CS, AI).

Edit:

Code for creating the linked list:

struct Student *add(struct Student *head) {
struct Student *student = (struct Student *)malloc(sizeof(struct Student));
student = inputStudent(); //function to take input from user about student fields
student->next = NULL;
if (head == NULL) {
/* if head is NULL, set student as the new head */
head = student;
} else {
/* if list is not empty, insert student in beginning of head */
student->next = head;
head = student;
}
return head;
}

There are multiple issues:

• char gender[6]; is too short to contain the string female.

• printf("Study Program: %n\n", temp->study_program->p_name); instead of %n, you should use %s

• scanf("%n", &p); you should use %d to convert an int value.

• scanf("%s", n); is risky: to avoid buffer overflows, you should use %49s for ch == 2 and %9s for ch == 3

• function add allocates memory for a Student structure but the pointer gets immediately overwritten by the result of inputStudent, which you did not provide. The memory is lost. Note also that inserting at the beginning of the list does not require special casing the empty string. Here is a simplified version:

  struct Student *add(struct Student *head) {
  struct Student *student = inputStudent();
  student->next = head;
  return student;
  }
  

• the function display outputs the full list of students and their details. If you do not get any output, the list must be empty or the head of the list must have been set to NULL in an unexpected way.

• for case ch == 1, the input does not store the number into p (because of the %n instead of %d), which would explain why no student is never found. Function display() seems to be expected to output a single student, but your implementation outputs the full list.