hi was wondering can anyone help me
whenever i run this on Visual Studio, it keeps exiting with code 0
Code:#include "stdafx.h" #include "stdio.h" // NULL defined here #include "stdlib.h" // malloc function here #include <string.h> //for handling strings #include <ctype.h> char reg_num[21]; //used in get_new_value struct TAXI_STRUCT struct TaxiNode { char* pszRegistrationNo; TaxiNode* pNext; TaxiNode* pPrevious; }; struct TaxiQueue { TaxiNode* pFirstTaxi; TaxiNode* pLastTaxi; }; typedef struct node *Listpointer; /*typedef struct node { char value[21]; struct node *next; }*Listpointer; */ //global variables //prototypes void menu(char choice[21]); void read_strings(char s [21], int n); void get_new_value(Listpointer ptr); void arrive(Listpointer ptr); void print(Listpointer ptr); int search(Listpointer ptr, char search_string[]); void leave(Listpointer ptr); void front(Listpointer ptr); void back(Listpointer ptr); void empty(Listpointer ptr); c.: #include "linkedlist.h" int main() { //variable declarations char choice[21]; char search_string[21]; int diff; //for strcmp() int done; Listpointer list; //initialise head of list list = (Listpointer)malloc(sizeof(struct node)); list -> next = NULL; strcpy(list -> value, "EMPTY"); //call the menu menu(choice); diff = strcmp(choice, "exit"); while(diff != 0) { done = 0; diff = strcmp(choice, "arrive"); //arrive choice if(diff == 0) { get_new_value(list); arrive(list); done = 1; } diff = strcmp(choice, "leave"); //leave choice if(diff == 0) { leave(list); done = 1; } diff = strcmp(choice, "search"); //search choice if(diff == 0) { printf("Enter a registration number:\n"); read_strings(search_string, 1); search(list,search_string); done = 1; } diff = strcmp(choice, "print"); //print choice if(diff == 0) { print(list); done = 1; } diff = strcmp(choice, "front"); //front choice if(diff == 0) { front(list); done = 1; } diff = strcmp(choice, "back"); //back choice if(diff == 0) { back(list); done = 1; } diff = strcmp(choice, "empty"); //empty choice if(diff == 0) { empty(list); done = 1; } //default choice if(done == 0) printf("Choice not recognised. "); //recall menu menu(choice); diff = strcmp(choice,"exit"); } return (1); } //system menu void menu(char choice[21]) { //display the menue printf("Please choose from one of the following\n"); printf("1.Arrive\n"); printf("2.Depart\n"); printf("3.Print\n"); printf("4.Find\n"); printf("0.exit\n"); read_strings(choice, 1); printf("\n"); } //read in a string to a given array void read_strings(char s [21], int n) { int i; for(i = 0; i < n; i++) { gets(s[i]); } } //validates the value to be entered into the list void get_new_value(Listpointer ptr) { int done = 1; int diff = 0; //for strcmp() int i; while(done == 1) { done = 0; printf("enter the registration number, 'empty' to abort\n"); read_strings(reg_num, 1); //convert to lower case for(i = 0; reg_num[i]; i++) { reg_num[i] = toupper(reg_num[i]); } //clear any symbols //check for abort entry diff = strcmp(reg_num,"EMPTY"); if(diff != 0) { //if abort entry found, set done to 1 done = 1; } if(done == 1) { done = 0; while(ptr != NULL) { // not end diff = strcmp(ptr -> value, reg_num); if((diff == 0) && (done != 1)) { done = 1; //found reg } ptr = ptr -> next; } // end while if(done == 1) { //error message for car found in array. printf("That car is already in the list\n"); } } } } void arrive(Listpointer ptr) { Listpointer new; //now declared here int diff; //for strcmp() diff = strcmp(reg_num, "EMPTY"); if(diff != 0) { while(ptr -> next != NULL) { ptr = ptr -> next; } new = (Listpointer)malloc(sizeof(struct node)); strcpy(new -> value, reg_num); ptr -> next = new; new -> next = NULL; } else { printf("Car not added\n"); } } void leave(Listpointer ptr) { Listpointer delete; //now declared here if(ptr -> next != NULL) { printf("taxi %s has left the rank\n", ptr -> next -> value); delete = (Listpointer)malloc(sizeof(struct node)); delete -> next = ptr -> next; if(ptr -> next == NULL) { free(ptr -> next); } else { ptr -> next = (ptr -> next -> next); } free(delete -> next); free(delete); } else { printf("the list is currently empty\n"); } } int search(Listpointer ptr, char search_string[]) { int diff; //for strcmp() int i; int taxiNumber = 0; //convert to lower case for(i = 0; search_string[i]; i++) { search_string[i] = toupper(search_string[i]); } while(ptr != NULL) { diff = strcmp(ptr -> value, search_string); if(diff == 0) { printf("taxi %s is %d from the top of the list\n", search_string, taxiNumber); return (1); } ptr = ptr -> next; taxiNumber ++; } printf("taxi %s not found\n", search_string); return (0); } void print(Listpointer ptr) { int taxiNumber = 0; int diff; //for strcmp() while(ptr != NULL) { diff = strcmp(ptr -> value, "EMPTY"); if(diff != 0) { printf("%d. %s\n", taxiNumber, ptr -> value); } taxiNumber ++; ptr = ptr -> next; } } void front(Listpointer ptr) { if(ptr -> next != NULL) { ptr = ptr -> next; printf("The taxi at the front of the list is %s\n", ptr -> value); } else { printf("The queue is currently empty\n"); } } void back(Listpointer ptr) { if(ptr -> next != NULL) { while(ptr -> next != NULL) { ptr = ptr -> next; } printf("The taxi at the back of the queue is %s\n", ptr -> value); } else { printf("The list is currently empty\n"); } } void empty(Listpointer ptr) { if(ptr -> next != NULL) { printf("The list is not empty\n"); } else { printf("The list is empty\n"); } }
