Question

create case 4 

#include <stdio.h>
int main(void) {
        int counter;
        int choice;
        FILE *fp;
        char item[100];
        while(1) {
                printf("Welcome to my shopping list\n\n");
                printf("Main Menu:\n");
                printf("1. Add to list\n");
                printf("2. Print List\n");
                printf("3. Delete List\n");
                printf("4. Remove an item from the List\n");
                printf("5. Exit\n\n");


                scanf("%i", &choice);
                switch(choice) {
                        case 1: //add to list
                                //get the input from the user
                                printf("Enter item: ");
                                scanf("%s", item);
                                //open the file
                                fp = fopen("list.txt","a");
                                //write to the file
                                fprintf(fp, "\n%s", item);
                                //close the file
                                fclose(fp);
                        break;
                        case 2: //print list
                                //open the file
                                fp = fopen("list.txt","r");
                                //while we are not at the end of the file
                                counter = 1;

                                //cheat to make feof work! 
                                char c = fgetc(fp);
                                ungetc(c, fp);
                                while (!feof(fp)) {
                                        //read in a line of data
                                        fscanf(fp, "%s", item);
                                        //print the data
                                        printf("%i. %s\n", counter,item);
                                        counter++;
                                }
                                //close the file
                                fclose(fp);
                        break;
                        case 3: //erase list
                                //truncate the file
                                fp = fopen("list.txt","w");
                                fclose(fp);


                        break;
                        case 4: //homework: remove an item from the list;

                        /*
                                Method 1:
                                        0) Get the item number the user wants to delete
                                        char data[100][100];
                                        1) Create an array of strings
                                        2) Loop over the items in the list, loading into the array
                                                -skip if it's the item the user wants to delete
                                        3) Loop over the array, writing out to the file. 


                        */

                        break;
                        case 5: //end program
                                return 0; 
                        break;




                }

        }

Answer 1

#include <stdio.h>
int main(void) {
        int counter;
        int choice;
        int item_no;
        FILE *fp;
        char c;
        char item[100];
        while(1) {
                printf("Welcome to my shopping list\n\n");
                printf("Main Menu:\n");
                printf("1. Add to list\n");
                printf("2. Print List\n");
                printf("3. Delete List\n");
                printf("4. Remove an item from the List\n");
                printf("5. Exit\n\n");

                scanf("%i", &choice);
                switch(choice) {
                        case 1: //add to list
                                //get the input from the user
                                printf("Enter item: ");
                                scanf("%s", item);
                                //open the file
                                fp = fopen("list.txt","a");
                                //write to the file
                                fprintf(fp, "\n%s", item);
                                //close the file
                                fclose(fp);
                        break;
                        case 2: //print list
                                //open the file
                                fp = fopen("list.txt","r");
                                //while we are not at the end of the file
                                counter = 1;

                                //cheat to make feof work!
                                c = fgetc(fp);
                                ungetc(c, fp);
                                while (!feof(fp)) {
                                        //read in a line of data
                                        fscanf(fp, "%s", item);
                                        //print the data
                                        printf("%i. %s\n", counter,item);
                                        counter++;
                                }
                                //close the file
                                fclose(fp);
                        break;
                        case 3: //erase list
                                //truncate the file
                                fp = fopen("list.txt","w");
                                fclose(fp);

                        break;
                        case 4: //homework: remove an item from the list;

                                fp = fopen("list.txt", "r");    //open the required file
                                printf("Enter the item no.");
                                scanf("%d", &item_no);          //take input for item number to be deleted

                                c = fgetc(fp);
                                ungetc(c, fp);
                                counter = 0;
                                char item_list[100];            //initialise an array of items

                                //read all items from the list
                                while (!feof(fp)) {
                                        //read in a line of data
                                        fscanf(fp, "%s", item);
                                        if(item_no != counter)      //condition to include all the items except the item to be deleted
                                            item_list[counter] = item;
                                        counter++;
                                }
                                //truncate the file
                                fp = fopen("list.txt","w");

                                fp = fopen("list.txt", "a");
                                //write to the file

                                int i = 0;
                                while(i < counter){
                                    fprintf(fp, "\n%s", item_list[i]);
                                    i++;
                                }
                                //close the file
                                fclose(fp);
                                /*
                                Method 1:
                                        0) Get the item number the user wants to delete
                                        char data[100][100];
                                        1) Create an array of strings
                                        2) Loop over the items in the list, loading into the array
                                                -skip if it's the item the user wants to delete
                                        3) Loop over the array, writing out to the file.
                            */

                        break;
                        case 5: //end program
                                return 0;
                        break;
                }

        }

}