psbhatnagar / 5.c

/* * Ex. No. 5: IMPLEMENTATION OF LINKED LIST * Student Record Management System using a singly linked list * Supports: INSERT (beginning/end/position), DELETE (beginning/end/position), * SEARCH, DISPLAY */ #include <stdio.h> #include <stdlib.h> #include <string.h> #define NAME_LEN 50 struct Node { int regNo; char name[NAME_LEN]; struct Node *next; }; struct Node *head = NULL; /* Count nodes in list */ int countNodes(void) { int count = 0; struct Node *cur = head; while (cur != NULL) { count++; cur = cur->next; } return count; } /* Allocate and fill a new node */ struct Node *makeNode(int regNo, const char *name) { struct Node *node = (struct Node *)malloc(sizeof(struct Node)); node->regNo = regNo; strncpy(node->name, name, NAME_LEN - 1); node->name[NAME_LEN - 1] = '\0'; node->next = NULL; return node; } /* i) Insert at Beginning */ void insertBeginning(int regNo, const char *name) { struct Node *node = makeNode(regNo, name); node->next = head; head = node; printf("Inserted at beginning.\n"); } /* ii) Insert at End */ void insertEnd(int regNo, const char *name) { struct Node *node = makeNode(regNo, name); if (head == NULL) { head = node; } else { struct Node *cur = head; while (cur->next != NULL) cur = cur->next; cur->next = node; } printf("Inserted at end.\n"); } /* iii) Insert at a Given Position (1-based) */ void insertAtPosition(int pos, int regNo, const char *name) { int size = countNodes(); if (pos < 1 || pos > size + 1) { printf("Invalid position.\n"); return; } if (pos == 1) { insertBeginning(regNo, name); return; } struct Node *prev = head; for (int i = 1; i < pos - 1; i++) prev = prev->next; struct Node *node = makeNode(regNo, name); node->next = prev->next; prev->next = node; printf("Inserted at position %d.\n", pos); } /* iv) Delete from Beginning */ void deleteBeginning(void) { if (head == NULL) { printf("List is empty.\n"); return; } struct Node *doomed = head; head = head->next; free(doomed); printf("Deleted from beginning.\n"); } /* v) Delete from End */ void deleteEnd(void) { if (head == NULL) { printf("List is empty.\n"); return; } if (head->next == NULL) { free(head); head = NULL; printf("Deleted from end.\n"); return; } struct Node *cur = head; while (cur->next->next != NULL) cur = cur->next; free(cur->next); cur->next = NULL; printf("Deleted from end.\n"); } /* vi) Delete from a Given Position (1-based) */ void deleteAtPosition(int pos) { int size = countNodes(); if (size == 0) { printf("List is empty.\n"); return; } if (pos < 1 || pos > size) { printf("Invalid position.\n"); return; } if (pos == 1) { deleteBeginning(); return; } struct Node *prev = head; for (int i = 1; i < pos - 1; i++) prev = prev->next; struct Node *doomed = prev->next; prev->next = doomed->next; free(doomed); printf("Deleted position %d.\n", pos); } /* vii) Search by register number */ void search(int regNo) { struct Node *cur = head; int pos = 1; while (cur != NULL) { if (cur->regNo == regNo) { printf("Found: RegNo=%d, Name=%s, Position=%d\n", cur->regNo, cur->name, pos); return; } cur = cur->next; pos++; } printf("Register number %d not found.\n", regNo); } /* viii) Display all students */ void display(void) { if (head == NULL) { printf("List is empty.\n"); return; } struct Node *cur = head; int pos = 1; printf("--- Student Records ---\n"); while (cur != NULL) { printf("%d) RegNo=%d, Name=%s\n", pos, cur->regNo, cur->name); cur = cur->next; pos++; } } /* Free all remaining nodes before exit */ void freeList(void) { struct Node *cur = head; while (cur != NULL) { struct Node *next = cur->next; free(cur); cur = next; } head = NULL; } void readName(char *name) { scanf(" %49[^\n]", name); } int main(void) { int choice, regNo, pos; char name[NAME_LEN]; do { printf("\n===== Student Record Management System =====\n"); printf("1. Insert at Beginning\n"); printf("2. Insert at End\n"); printf("3. Insert at a Given Position\n"); printf("4. Delete from Beginning\n"); printf("5. Delete from End\n"); printf("6. Delete from a Given Position\n"); printf("7. Search\n"); printf("8. Display\n"); printf("9. Exit\n"); printf("Enter your choice: "); scanf("%d", &choice); switch (choice) { case 1: printf("Enter register number: "); scanf("%d", &regNo); printf("Enter name: "); readName(name); insertBeginning(regNo, name); break; case 2: printf("Enter register number: "); scanf("%d", &regNo); printf("Enter name: "); readName(name); insertEnd(regNo, name); break; case 3: printf("Enter position: "); scanf("%d", &pos); printf("Enter register number: "); scanf("%d", &regNo); printf("Enter name: "); readName(name); insertAtPosition(pos, regNo, name); break; case 4: deleteBeginning(); break; case 5: deleteEnd(); break; case 6: printf("Enter position: "); scanf("%d", &pos); deleteAtPosition(pos); break; case 7: printf("Enter register number to search: "); scanf("%d", &regNo); search(regNo); break; case 8: display(); break; case 9: printf("Exiting...\n"); break; default: printf("Invalid choice.\n"); } } while (choice != 9); freeList(); return 0; }