Student Management System.
  /* Student Management System */

#include <stdio.h>
#include <alloc.h>
#include <stdlib.h>
#include <conio.h>
#include <ctype.h>
#include <string.h>

/* function prototypes */

void create( char *, int, int, char * );
void printnode( struct node * );
void display( struct node * );
struct node * search( struct node *, int );
void delete( struct node * );

/* definition of a data node for holding student information */

struct node {
char name[20];
int age;
int studentID;
char course[15];
struct node *next;
};

/* head points to first node in list, end points to last node in list */
/* initialise both to NULL, meaning no nodes in list yet */

struct node *head = (struct node *) NULL;
struct node *end = (struct node *) NULL;

/* this initialises a node, allocates memory for the node, and returns */
/* a pointer to the new node. Must pass it the node details, name and id */

void create( char *name, int age, int studentID, char *course){
struct node *ptr;
ptr = (struct node *) calloc( 1, sizeof(struct node ) );
if( ptr == NULL ) /* error allocating node? */
printf("List is null"); /* then return NULL, else */
else { /* allocated node successfully */
strcpy( ptr->name, name ); /* fill in name details */
ptr->age = age; /* copy id details */
ptr->studentID = studentID;
strcpy(ptr->course,course);
if( head == NULL ) /* if there are no nodes in list, then */
head = ptr; /* set head to this new node */
end->next = ptr; /* link in the new node to the end of the list */
ptr->next = NULL; /* set next field to signify the end of list */
end = ptr; /* return pointer to new node */
}
}

/* this prints the details of a node, eg, the name and id */
/* must pass it the address of the node you want to print out */
void printnode( struct node *ptr ){
printf("\n");
printf("Student ID : - %d \n", ptr->studentID);
printf("Name of Student : - %s \n", ptr->name );
printf("Age : - %d \n", ptr->age );
printf("Course Carried : - %s \n", ptr->course);
}

/* this prints all nodes from the current address passed to it. If you */
/* pass it 'head', then it prints out the entire list, by cycling through */
/* each node and calling 'printnode' to print each node found */

void display( struct node *ptr ){
while( ptr != NULL ){ /* continue whilst there are nodes left */
printnode( ptr ); /* print out the current node */
ptr = ptr->next; /* goto the next node in the list */
}
}

/* search the list for a name, and return a pointer to the found node */
/* accepts a studentID to search for, and a pointer from which to start. If */
struct node * search( struct node *ptr, int studentID ){
while( ptr->studentID!=studentID ) { /* whilst name not found */
ptr = ptr->next; /* goto the next node */
if( ptr == NULL ) /* stop if we are at the */
break; /* of the list */
}
return ptr; /* return a pointer to */
} /* found node or NULL */

/* deletes the specified node pointed to by 'ptr' from the list */
void delete( struct node *ptr ){
struct node *temp, *prev;
temp = ptr; /* node to be deleted */
prev = head; /* start of the list, will cycle to node before temp */
if( temp == prev ) { /* are we deleting first node */
head = head->next; /* moves head to next node */
if( end == temp ) /* is it end, only one node? */
end = end->next; /* adjust end as well */
free( temp ); /* free space occupied by node */
printf("Node has been deleted ! ");
}
else{ /* if not the first node, then */
while( prev->next != temp ){ /* move prev to the node before*/
prev = prev->next; /* the one to be deleted */
}
prev->next = temp->next; /* link previous node to next */
if( end == temp ) /* if this was the end node, */
end = prev; /* then reset the end pointer */
free( temp ); /* free space occupied by node */
}
}

/* main() the start of management system */
main(){
char name[20], course[20];
int age, ch = 1,studentID;
struct node *ptr;
clrscr();
while( ch != 5 ) {
printf("\n \t ***** Student Management System ***** \n");
printf("1. Display all student List \n");
printf("2. Add a student \n");
printf("3. Delete a student \n");
printf("4. Search student\n");
printf("5. Exit\n");
printf("Please select your choice : - ");
scanf("%d", &ch );

/* statements for handling user instruction */
switch( ch ){

/* Display all nodes in a list */
case 1:
display( head );
break;

/* Create new node in a List */
case 2:
printf("\n ***** Data entry procedure ***** \n");
printf("\n Enter student ID : - ");
scanf("%d",&studentID);
printf("\n Enter student name : - ");
scanf("%s", name );
printf("\n Enter student age : - ");
scanf("%d", &age );
printf("\n Enter course name : - ");
scanf("%s", course);
create( name, age, studentID, course );
break;

/* delete a node containing entered studentID */
case 3:
printf("Enter student ID : - ");
scanf("%d",&studentID );
ptr = search( head, studentID);
delete( ptr);
break;

/*Search and display the node information whose studentID entered by user*/
case 4:
printf("Enter in Student ID :- ");
scanf("%d",&studentID );
ptr = search( head, studentID);
if( ptr ==NULL ){
printf("Student ID - %d not found\n", studentID );
}
else
printnode( ptr );
break;
}
}
}