C program to illustrate the operations of singly linked list

/* Write a C program to illustrate the operations of singly linked list */

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
#define MAX 30

struct EMP
{
int  empno;
char empName[MAX];
    char designation[MAX];
    struct EMP *next;
};

/*********************************************************************/
/* Function to insert a node at the front of the linked list.        */
/* front: front pointer, id: employee ID, name: employee name        */
/* desg: Employee designation     */
/* Returns the new front pointer.                                    */
/*********************************************************************/

struct EMP* insert(struct EMP *front, int id, char name[], char desg[])
{
    struct EMP *newnode;

    newnode = (struct EMP*) malloc(sizeof(struct EMP));

    if (newnode == NULL)
    {
 printf("\nAllocation failed\n");
        exit(2);
    }
    newnode->empno = id;
    strcpy(newnode->empName, name);
     strcpy(newnode->designation, desg);
    newnode->next = front;
    front = newnode;
    return(front);
}                             /*End of insert() */

/* Function to display a node in a linked list */
void printNode(struct EMP *p)
{
printf("\nEmployee Details...\n");
printf("\nEmp No  : %d", p->empno);
printf("\nName           : %s", p->empName);
printf("\nDesignation    : %s\n", p->designation);
printf("-------------------------------------\n");
}                               /*End of printNode() */

/* ********************************************************/
/* Function to deleteNode a node based on employee number     */
/* front: front pointer, id: Key value                    */
/* Returns: the modified list.                            */
/* ********************************************************/

struct EMP* deleteNode(struct EMP *front, int id)
{
    struct EMP *ptr;
    struct EMP *bptr;    /* bptr is pointing to the node behind ptr */


    if (front->empno == id)
    {
ptr = front;
printf("\nNode deleted:");
        printNode(front);
        front = front->next;
free(ptr);
        return(front);
    }

    for(ptr=front->next, bptr=front; ptr!=NULL; ptr=ptr->next, bptr=bptr->next)
    {
if (ptr->empno == id)
{
                printf("\nNode deleted:");
printNode(ptr);
bptr->next = ptr->next;
free(ptr);
return(front);
        }
    }
    printf("\nEmployee Number %d not found ", id);
    return(front);
}                             /*End of deleteNode() */

/*****************************************************************/
/* Function to search the nodes in a linear fashion based emp ID */
/* front: front pointer, key: key ID.                             */
/*****************************************************************/
void search(struct EMP *front, int key)
{
struct EMP *ptr;

for (ptr = front; ptr != NULL; ptr = ptr -> next)
{
 if (ptr->empno == key)
 {
            printf("\nKey found:");
printNode(ptr);
            return;
        }
    }
printf("\nEmployee Number %d not found ", key);
}                           /*End of search() */

/* Function to display the linked list */
void display(struct EMP *front)
{
struct EMP *ptr;

for (ptr = front; ptr != NULL; ptr = ptr->next)
{
 printNode(ptr);
}
}                         /*End of display() */

/* Function to display the menu of operations on a linked list */
void menu()
{
printf("---------------------------------------------\n");
printf("Press 1 to INSERT a node into the list       \n");
printf("Press 2 to DELETE a node from the list       \n");
printf("Press 3 to DISPLAY the list                  \n");
printf("Press 4 to SEARCH the list                   \n");
printf("Press 5 to EXIT                              \n");
printf("---------------------------------------------\n");
}                     /*End of menu() */

/* Function to select the option */
char option()
{
char choice;

printf("\n\n>> Enter your choice: ");
switch(choice=getche())
{
 case '1':
 case '2':
         case '3':
         case '4':
 case '5':   return(choice);
         default :    printf("\nInvalid choice.");
}
return choice;
}       /*End of option() */

/* The main() program begins */
void main()
{
    struct EMP *linkList;
    char name[21], desig[51];
    char choice;
    int eno;

    linkList = NULL;

    printf("\nWelcome to demonstration of singly linked list\n");

    menu();     /*Function call */

    do {
 choice = option();          /*to choose oeration to be performed */

 switch(choice)
 {
case '1': printf("\nEnter the Employee Number      : ");
scanf("%d", &eno);

printf("Enter the Employee name        : ");
fflush(stdin);
gets(name);

printf("Enter the Employee Designation : ");
gets(desig);

linkList = insert(linkList, eno, name, desig);
break;

case '2': printf("\n\nEnter the employee number to be deleted: ");
scanf("%d", &eno);

linkList = deleteNode(linkList, eno);
break;

case '3': if (linkList == NULL)
{
printf("\nList empty.");
break;
}
display(linkList);
break;

case '4': printf("\n\nEnter the employee number to be searched: ");
scanf("%d", &eno);

search(linkList, eno);
break;

case '5': break;
        }
} while (choice != '5');
}     /*End fo main()*/

/*------------------------------------------------------------------------------
Output

Welcome to demonstration of singly linked list
---------------------------------------------
Press 1 to INSERT a node into the list
Press 2 to DELETE a node from the list
Press 3 to DISPLAY the list
Press 4 to SEARCH the list
Press 5 to EXIT
---------------------------------------------


>> Enter your choice: 1
Enter the Employee Number      : 1234
Enter the Employee name        : Keerthi
Enter the Employee Designation : Engineer


>> Enter your choice: 1
Enter the Employee Number      : 2345
Enter the Employee name        : Srinivasan
Enter the Employee Designation : Specilist


>> Enter your choice: 1
Enter the Employee Number      : 4567
Enter the Employee name        : Annapoorna
Enter the Employee Designation : Project Manager


>> Enter your choice: 3
Employee Details...

Emp No    : 4567
Name        : Annapoorna
Designation : Project Manager
-------------------------------------

Employee Details...

Emp No    : 2345
Name        : Srinivasan
Designation : Specilist
-------------------------------------

Employee Details...

Emp No    : 1234
Name        : Keerthi
Designation : Engineer
-------------------------------------


>> Enter your choice: 2

Enter the employee number to be deleted: 2345

Node deleted:
Employee Details...

Emp No    : 2345
Name        : Srinivasan
Designation : Specilist
-------------------------------------


>> Enter your choice: 3
Employee Details...

Emp No    : 4567
Name        : Annapoorna
Designation : Project Manager
-------------------------------------

Employee Details...

Emp No    : 1234
Name        : Keerthi
Designation : Engineer
-------------------------------------


>> Enter your choice: 4

Enter the employee number to be searched: 2345

Employee Number 2345 not found

>> Enter your choice: 5

------------------------------------------------------------------------------*/