Below is the first bit of a linked list program that I am trying to learn about. Can someone please tell me why the 4 lines in bold are required? I am confused as they seem to be just the name of functions that occur later in the program, however when I write programs I have never declared a function in this way before. Why would it be correct to write those 4 lines, in addition to the actual functions later on?
Thankyou,
Chris
Code:#include <stdio.h> #include <stdlib.h> /* node type for linked list */ struct node { int val; struct node *next; }; /* will point to beginning of list */ struct node *list = NULL; void print_list(void); void add_item(char flag); void delete_item(void); void delete_list(void); int main(void) { char choice; char line[50]; printf("Linked list demonstration (integers)\n"); while (choice != 'q') { printf("(1) Print contents of list\n"); printf("(2) Add item to beginning of list\n"); printf("(3) Add item to end of list\n"); printf("(4) Delete item from list\n"); printf("(5) Delete entire list\n"); printf("(q) Quit\n"); printf("Select an option: "); fgets(line, sizeof(line), stdin); sscanf(line, "%c", &choice); switch (choice) { case '1' : print_list(); break; case '2' : add_item('b'); /* add to beginning */ break; case '3' : add_item('e'); /* add to end */ break; case '4' : delete_item(); break; case '5' : delete_list(); break; case 'q' : printf("Cleaning up...\n"); delete_list(); /* unnecessary, but good habit */ break; default : printf("Error - invalid input\n"); break; } } return 0; } void print_list(void) { if.............