Main drive program to process a linked list of strings

Self_referential_struct.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define NULL 0

struct  list_element
{
	char item[40];
	struct list_element *next;
};


typedef struct list_element node;

int menu(void);
void create(node *pt);
node *insert(node *pt);
node *remove(node *pt);
void display(node *pt);

void main(){

	node *start;
	int choice;

	do{
		choice = menu();
		start = (node *)malloc(sizeof(node));     // alocate some memory for start :) 
		switch (choice)
		{
		case 1:
			
			create(start);
			printf_s("\n");
			display(start);
			continue;

		case 2:
			start = insert(start);
			printf_s("\n");
			display(start);
			continue;

		case 3:
			start = remove(start);
			printf_s("\n");
			display(start);
			continue;

		default:
			printf_s("End of computaion");
			break;
		}
	} while (choice != 4);
}



int menu(){

	int choice;

	do{
		printf_s("\nMain menu : \n\n");
		printf_s("      1 - CREATE the link list \n ");
		printf_s("     2 - ADD a component  \n ");
		printf_s("     3 - DELETE a component  \n ");
		printf_s("     4 - END \n ");


		printf_s("\n\nPlease Enter your choice (1,2,3,4) ->  ");
		scanf_s("%d", &choice);

		if (choice < 1 || choice>4){
			printf_s("\n Error - Please try again ");
		}

	} while (choice < 1 || choice>4);

	printf_s("\n\n");
	return(choice);
}

// Create a link list 
void create(node *record){

	//argument points to the current node 

	printf_s("Data items (type \' END \' when finish) : ");
	scanf_s("%s", record->item, 40);

	if (strcmp(record->item, "END") == 0 || strcmp(record->item, "end") == 0){
		record->next = NULL;
	}
	else{
		// alocate space from next node 
		record->next = (node *)malloc(sizeof(node));
		create(record->next);
	}

	return;
}

// display the link list
void display(node *record){

	// argument points to the current node 
	
	if ( record->next != 0 ){
		printf_s("%s\n", record->item, 40);
		display(record->next);
	}
	return;
}


node *insert(node *frist){
	
	/*add one componet to the linked list return a pointer to beginning of the modified list */

	// argu points to the frist node 

	node *locate(node*, char[]);
	node *newrecord;
	node *tag;

	char newitem[40];
	char target[40];

	printf_s("New Data item : ");
	scanf_s("%s", newitem, 40);
	printf_s("Place before (type \'END\' if last) : ");
	scanf_s("%s", target, 40);

	if (strcmp(frist->item, target) == 0){
		// new node list in list 
		newrecord = (node *)malloc(sizeof(node));
		strcpy_s(newrecord->item, newitem);
		newrecord->next = frist;
		frist = newrecord;
	}
	else
	{
		// insert new node after an existing node 
		tag = locate(frist, target);

			if (tag == 0){
				printf_s("\n\nMatch not found ---- try again later ");

			}
			else{
				newrecord = (node *)malloc(sizeof(node));
				strcpy_s(newrecord->item, newitem);
				newrecord->next = tag->next;
				tag->next = newrecord;
			}
	}
	return(frist);
}


//locate node 
node *locate(node *record, char target[]){

	/* return a pointer to the node BEFORE the target node the frist argu point to the current node the second argu is the target strg */


	if (strcmp(record->next->item, target) == 0){
		return(record);
	} else if(record->next->next==0){
		return(NULL);
	}
	else
	{
		locate(record->next, target);
	}

}



node *remove(node *frist){

	/* remove (delete) one component from the linked list return a pointer to beginning of the mdified list */

	// node the frist argu

	node *locate(node*, char[]);
	node *tag;
	node *temp;
	char target[40];

	printf_s("Data item to be delete :  ");
	scanf_s("%s", target, 40);

	if (strcmp(frist->item, target) == 0){
		// del the frist node 
		temp = frist->next;
		free(frist);

		frist = temp;

	}
	else{

		// del a date item other then the frist 

		tag = locate(frist, target);
		if (tag == 0){
			printf_s("\nMatch not found ------- Please try again later \n");
		}
		else{
			temp = tag->next->next;
			free(tag->next);
			tag->next = temp;
		}

	}
	return(frist);

}