C Program to Implement Advanced Singly Linked List using Dynamic Memory Allocation

singly_linked_list_challenge

/*
----------------------------------------------
--- Author         : Ahmet Özlü
--- Mail           : ahmetozlu93@gmail.com
--- Date           : 1st September 2017
----------------------------------------------
*/

#include <stdio.h>
#include <malloc.h>
#define ISEMPTY printf("\nEMPTY LIST:");

// Node Declaration
struct node {
	int value;
	struct node *next;
};

typedef struct node snode;

snode* create_node(int);
void insert_node_first();
void insert_node_last();
void insert_node_pos();
void sorted_ascend();
void delete_pos();
void search();
void update_val();
void display();
void rev_display(snode *);

snode *newnode, *ptr, *prev, *temp;
snode *first = NULL, *last = NULL;

int main() {
	int ch;
	char ans = 'Y';

	while (ans == 'Y'||ans == 'y') {
	    printf("\n---------------------------------\n");
	    printf("\nOperations on singly linked list\n");
	    printf("\n---------------------------------\n");
	    printf("\n1.Insert node at first");
	    printf("\n2.Insert node at last");
	    printf("\n3.Insert node at position");
	    printf("\n4.Sorted Linked List in Ascending Order");
	    printf("\n5.Delete Node from any Position");
	    printf("\n6.Update Node Value");
	    printf("\n7.Search Element in the linked list");
	    printf("\n8.Display List from Beginning to end");
	    printf("\n9.Display List from end using Recursion");
	    printf("\n10.Exit\n");
	    printf("\n~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
	    printf("\nEnter your choice");
	    scanf("%d", &ch);

	    switch (ch) {
		    case 1: 
			printf("\n...Inserting node at first...\n");
			insert_node_first();
			break;
		    case 2: 
			printf("\n...Inserting node at last...\n");
			insert_node_last();
			break;
		    case 3: 
			printf("\n...Inserting node at position...\n");
			insert_node_pos();
			break;
		    case 4: 
			printf("\n...Sorted Linked List in Ascending Order...\n");
			sorted_ascend();
			break;
		    case 5: 
			printf("\n...Deleting Node from any Position...\n");
			delete_pos();
			break;
		    case 6: 
			printf("\n...Updating Node Value...\n");
			update_val();
			break;
		    case 7: 
			printf("\n...Searching Element in the List...\n");
			search();
			break;
		    case 8: 
			printf("\n...Displaying List From Beginning to End...\n");
			display();
			break;
		    case 9: 
			printf("\n...Displaying List From End using Recursion...\n");
			rev_display(first);
			break;
		    case 10: 
			printf("\n...Exiting...\n");
			return 0;
			break;
		    default: 
			printf("\n...Invalid Choice...\n");
			break;
	    }
	    printf("\nYOU WANT TO CONTINUE (Y/N)");
	    scanf(" %c", &ans);
	}

	return 0;
}

// Creating Node
snode* create_node(int val) {
	newnode = (snode *)malloc(sizeof(snode));
	
	if (newnode == NULL) {
	    printf("\nMemory was not allocated");
	    return 0;
	}
	else {
	    newnode->value = val;
	    newnode->next = NULL;
	    return newnode;
	}
}

// Inserting Node at First
void insert_node_first() {
	int val;
	printf("\nEnter the value for the node:");
	scanf("%d", &val);
	newnode = create_node(val);

	if (first == last && first == NULL) {
	    first = last = newnode;
	    first->next = NULL;
	    last->next = NULL;
	}
	else {
	    temp = first;
	    first = newnode;
	    first->next = temp;
	}

	printf("\n----INSERTED----");    
}

// Inserting Node at Last
void insert_node_last() {
	int val;
	printf("\nEnter the value for the Node:");    
	scanf("%d", &val);
	newnode = create_node(val);

	if (first == last && last == NULL) {
	    first = last = newnode;
	    first->next = NULL;
	    last->next = NULL;
	}
	else {
	    last->next = newnode;
	    last = newnode;
	    last->next = NULL;
	}

	printf("\n----INSERTED----");
}    

// Inserting Node at position
void insert_node_pos() {
	int pos, val, cnt = 0, i;
	printf("\nEnter the value for the Node:");
	scanf("%d", &val);
	newnode = create_node(val);
	printf("\nEnter the position ");
	scanf("%d", &pos);
	ptr = first;
	while (ptr != NULL) {
	    ptr = ptr->next;
	    cnt++;
	}

	if (pos == 1) {
	    if (first == last && first == NULL) {
		first = last = newnode;
		first->next = NULL;
		last->next = NULL;
	    }
	    else {
		temp = first;
		first = newnode;
		first->next = temp;
	    }

	    printf("\nInserted");
	}
	else if (pos>1 && pos<=cnt) {
	    ptr = first;
	    for (i = 1;i < pos;i++) {
		prev = ptr;
		ptr = ptr->next;
	    }
	    prev->next = newnode;
	    newnode->next = ptr;
	    printf("\n----INSERTED----");
	}
	else {
	    printf("Position is out of range");
	}
}

// Sorted Linked List
void sorted_ascend() {
	snode *nxt;
	int t;

	if (first == NULL) {
	    ISEMPTY;
	    printf(":No elements to sort\n");
	}
	else {
	    for (ptr = first;ptr != NULL;ptr = ptr->next) {
		for (nxt = ptr->next;nxt != NULL;nxt = nxt->next) {
		    if (ptr->value > nxt->value) {    
		        t = ptr->value;
		        ptr->value = nxt->value;
		        nxt->value = t;
		    }
		}
	    }

	    printf("\n---Sorted List---");

	    for (ptr = first;ptr != NULL;ptr = ptr->next) {
		printf("%d\t", ptr->value);
	    }
	}
}

// Delete Node from specified position in a non-empty list
void delete_pos() {
	int pos, cnt = 0, i;

	if (first == NULL) {
	    ISEMPTY;
	    printf(":No node to delete\n");
	}
	else {
	    printf("\nEnter the position of value to be deleted:");
	    scanf(" %d", &pos);
	    ptr = first;

	    if (pos == 1) {
		first = ptr->next;
		printf("\nElement deleted");    
	    }
	    else {
		while (ptr != NULL) {
		    ptr = ptr->next;
		    cnt = cnt + 1;
		}
		if (pos > 0 && pos <= cnt) {
		    ptr = first;
		    for (i = 1;i < pos;i++) {
		        prev = ptr;
		        ptr = ptr->next;
		    }
		    prev->next = ptr->next;
		}
		else {
		    printf("Position is out of range");
		}
	    free(ptr);
	    printf("\nElement deleted");
	    }
	}
}

// Updating Node value in a non-empty list
void update_val() {
	int oldval, newval, flag = 0;

	if (first == NULL) {
	    ISEMPTY;
	    printf(":No nodes in the list to update\n");
	}
	else {
	    printf("\nEnter the value to be updated:");
	    scanf("%d", &oldval);
	    printf("\nEnter the newvalue:");    
	    scanf("%d", &newval);

	    for (ptr = first;ptr != NULL;ptr = ptr->next) {
		if (ptr->value == oldval) {
		    ptr->value = newval;
		    flag = 1;
		    break;
		}
	    }

	    if (flag == 1) {
		printf("\nUpdated Successfully");
	    }
	    else {
		printf("\nValue not found in List");
	    }
	}    
}

// searching an element in a non-empty list
void search() {
	int flag = 0, key, pos = 0;

	if (first == NULL) {
	    ISEMPTY;
	    printf(":No nodes in the list\n");
	}
	else {
	    printf("\nEnter the value to search");
	    scanf("%d", &key);
	    for (ptr = first;ptr != NULL;ptr = ptr->next) {
		pos = pos + 1;
		if (ptr->value == key) {
		    flag = 1;
		    break;
		}
	    }
	    if (flag == 1) {
		printf("\nElement %d found at %d position\n", key, pos);
	    }
	    else {
		printf("\nElement %d not found in list\n", key);
	    }
	}    
}

// Displays non-empty List from Beginning to End
void display() {
	if (first == NULL) {
	    ISEMPTY;
	    printf(":No nodes in the list to display\n");
	}
	else {
	    for (ptr = first;ptr != NULL;ptr = ptr->next) {    
		printf("%d\t", ptr->value);
	    }
	}
}

// Display non-empty list in Reverse Order
void rev_display(snode *ptr) {
	int val;

	if (ptr == NULL) {
	    ISEMPTY;
	    printf(":No nodes to display\n");
	}
	else {
	    if (ptr != NULL) {
		val = ptr->value;
		rev_display(ptr->next);
		printf("%d\t", val);        
	    }
	}
}