Help please.

[Thermal]

I keep getting errors in my programming now it is giving me the unintinitlized local variable prev used. can anyone help me with this real fast, I have to go to bed soon.

#include <iostream>
#include <stdio.h>
#include <stdlib.h> /* has the malloc prototype */
#include <string.h> /* has the strcpy prototype */
#define TSIZE 45 /* size of array to hold title */


struct film
{
	char title[TSIZE];
	int rating;
	struct film * next; /* points to next struct in list */
};
void reverse(struct film* head)
{
	if (head == NULL);
	return;
	reverse(head->next);
	printf("Movie: %s Rating: %d\n", head->title, head->rating);
}
char * s_gets(char * st, int n);


int main(void)
{
	struct film * head = NULL;
	struct film * prev, *current;


	char input[TSIZE];


	/* Gather and store information				 */
	puts("Enter first movie title:");
	while (s_gets(input, TSIZE) != NULL && input[0] != '\0');
	{
		current = (struct film *) malloc(sizeof(struct film));


		if (head == NULL)	/* first structure */
			head = current;


		else                          /* subsequent structures */
			prev ->next = current;


		current->next = NULL;
		strcpy_s(current->title, input);


		puts("Enter your rating <0-10>:");
		scanf_s("%d", &current->rating);
		while (getchar() != '\n')
			continue;
		puts("Enter next movie title (empty line to stop):");
		prev = current;
	}
	/* Show list of movies						 */
	if (head == NULL)
		printf("No data entered. ");
	else
		printf("\What order do you want to print your list? 1. Input order 2. Reverse input order :");
	int choice;
	scanf_s("%d", &choice);//reading choice from user
	printf("Here is the movie list:\n");
	if (choice == 1){
		current = head;
		while (current != NULL)
		{
			printf("Movie: %s Rating: %d\n",
				current->title, current->rating); //it oprintd normally top to bottom
			current = current->next;
		}
	}
	else{
		printf("\nPrinting in reverse order\n");
		reverse(head);
	}
	/* Program done, so free allocated memory */
	current = head;
	while (current != NULL)
	{
		struct film * tmp = current->next;
		free(current);
		current = tmp;
	}
	printf("Bye!\n");
	system("PAUSE");
	return 0;
}

[stahta01]

Edit3: In C you can NOT declare variables anywhere in the code; you must do it only in the beginning of a block.

int choice;

if (head == NULL);
return;

You have a ";" after the ")" this is likely wrong.

Edit: If you indent your code and post it correctly in code tags you are likely to get more help.
Edit2: Decide if you are doing C or C++ programming! You should NOT include a C++ header in C code.

Tim S.

[Thermal]

I am using my textbook, and I was to copy the program and just add a loop in it to make it read the users input backward. SoI have to use the program as they have it setup. I can, however, show the indents didn't think it would have been that big of a deal not too since I'm sure I'm just missing something so simple. This is the error I am getting.
Error 2 error C4700: uninitialized local variable 'prev' used

#include <iostream>
#include <stdio.h>
#include <stdlib.h> /* has the malloc prototype */
#include <string.h> /* has the strcpy prototype */
#define TSIZE 45 /* size of array to hold title */


struct film
{
    char title[TSIZE];
    int rating;
    struct film * next; /* points to next struct in list */
};
void reverse(struct film* head)
{
    if (head == NULL)
    return;
    reverse(head->next);
    printf("Movie: %s Rating: %d\n", head->title, head->rating);
}
char * s_gets(char * st, int n);


int main(void)
{
    struct film * head = NULL;
    struct film * prev , *current;


    char input[TSIZE];


    /* Gather and store information                 */
    puts("Enter first movie title:");
    while (s_gets(input, TSIZE) != NULL && input[0] != '\0');
    {
        current = (struct film *) malloc(sizeof(struct film));


        if (head == NULL)    /* first structure */
            head = current;


        else                /* subsequent structures */
            prev->next = current;
            current->next = NULL;
        strcpy_s(current->title, input);


        puts("Enter your rating <0-10>:");
        scanf_s("%d", &current->rating);
        while (getchar() != '\n')
            continue;
        puts("Enter next movie title (empty line to stop):");
        prev = current;
    }
    /* Show list of movies                         */
    if (head == NULL)
        printf("No data entered. ");
    else
    printf("\What order do you want to print your list? 1. Input order 2. Reverse input order :");
    int choice;
    scanf_s("%d", &choice);//reading choice from user
    printf("Here is the movie list:\n");
    if (choice == 1){
        current = head;
        while (current != NULL)
        {
            printf("Movie: %s Rating: %d\n",
                current->title, current->rating); //it oprintd normally top to bottom
            current = current->next;
        }
    }
    else{
        printf("\nPrinting in reverse order\n");
        reverse(head);
    }
    /* Program done, so free allocated memory */
    current = head;
    while (current != NULL)
    {
        struct film * tmp = current->next;
        free(current);
        current = tmp;
    }
    printf("Bye!\n");
    system("PAUSE");
    return 0;
}

[stahta01]

Make a choice C++ or C; if C, use a C Compiler instead of a C++ Compiler!

Edit1:

Error 2 error C4700: uninitialized local variable 'prev' used

Why do you NOT init it to NULL?
Note, this will likely change it to a run-time error instead.

Tim S.

[swgh]

If that code is from a text book - chuck it out and get a modern C language text book - preferably one that teaches C99/11. Any author thinking the C++ headers belong in a C program does not deserve to be writing books. Also

system("pause");

Is a OS System command and should not be used to keep the console open. Use

getchar();

instead. Do not use getch() for this reason, as the conio,h header is outdated and not standard.