Queue testing problems

[Dr Saucie]

New to the C language and trying to write a test program for my queue, just wondering what I'm doing wrong. Im not really sure if i'm referencing things correctly.

here are my compiler errors:

gcc -Wall -ansi -pedantic queue.c queue.h test.c
queue.c: In function âdequeueâ:
queue.c:34: warning: passing argument 1 of âemptyâ from incompatible pointer type
queue.c:48: warning: cast from pointer to integer of different size
queue.c: In function âprintArrâ:
queue.c:73: warning: format â%dâ expects type âintâ, but argument 2 has type âint *â
queue.c: In function âfreeArrâ:
queue.c:84: error: expected declaration or statement at end of input
queue.c:84: error: expected declaration or statement at end of input

queue.c

#include <stdio.h>
#include <stdlib.h>
#include "queue.h"

void init ( Queue * qq)
{
	qq->cap = 26;
	qq->arr = malloc( sizeof(int) * qq->cap);
	qq->front = 0;
	qq->back = 0;
	qq->elements = 0;
 
}
void enqueue( Queue * qq, int num)
{
	if(qq->cap == qq->elements)
	{
		qq->arr = realloc(qq->arr, sizeof(int) * qq->cap);
		qq->arr[qq->back++] = num;
		qq->elements++;
	}
	else
	{
		qq->arr[ qq->back++ ] = num;
		qq->elements++;
	}
	
}

int dequeue( Queue * qq)
{
	int i;

	if(empty(qq->arr))
	{
		printf("ITS EMPTY!!\n");
	}
	else
	{

		qq->elements--;
		qq->arr[qq->front] = 0;
		for(i=0; i<qq->elements; i++)
		{
			qq->arr[i] = qq->arr[i+1];
		}
	}
	return (int)qq->arr;
}

int empty( Queue * qq)
{
	int test = 0;

	if(qq->arr == NULL)
	{
		test = 1;
	}
	return test;
}	

int length(Queue * qq)
{
	return qq->elements;
}

void printArr(Queue * qq)
{
	int i;
	
	for(i=0; i<qq->elements; i++)
	{
		printf("%d ", qq->arr);
	} 
}

void freeArr( Queue * qq)
{
	if(qq != NULL)
	{
		free(qq->arr);
		free(qq);
	{
}

queue.h

typedef struct
{
	int cap;
	int *arr;
	int front;
	int back;
	int elements;
} Queue;

void init (Queue * qq);
void enqueue( Queue * qq, int num );
int dequeue( Queue * qq);
int empty (Queue * qq);
int length ( Queue * qq);
void printArr(Queue * qq);
void freeArr ( Queue * qq);

test.c

#include <stdio.h>
#include <stdlib.h>
#include "queue.h"

int main()
{

	int choose = 0;
	int num;
	Queue q;

	printf("welcome to the queue ........");
	printf("1. enqueue\n");
	printf("2. dequeue\n");
	printf("3. print\n");
	printf("4. Check if queue is empty:\n");
	printf("5. get length\n");
	printf("6. free queue\n");
	
	scanf("%d", &choose);

	switch(choose)
	{
		case 1:
			scanf("Enter a number to engueue: %d\n", &num);
			enqueue(&q, num);
			break;
		case 2:
			dequeue(&q);
			break;
		case 3:
			printArr(&q);
			break;
		case 4:
			empty(&q);
			break;
		case 5:
			length(&q);
			break;
		case 6:
			freeArr(&q);
			break; 
	}
return 0;
}

[Epy]

In dequeue(): if(empty(qq->arr)) should probably be if(empty(qq)) since empty expects Queue*
You probably want to change the return statement of this function so you're actually returning the first value of qq->arr instead of an int cast of the pointer qq->arr.

In printArr(): You have to dereference qq->arr and somehow use i so that you can iterate through the array...you don't want to print out the same pointer address qq->element times.

In freeArr():  You have two {'s for the if statement, the last one needs to be a }

The nags about using code tags are really annoying. I shouldn't have had to of used them in this case.

[nadroj]

	if(empty(qq->arr))

You've declared "empty" to accept parameters of type "Queue*", but your passing qq->arr, which is type "int*". Either just pass "qq" or change "empty" to accept the different parameter.

return (int)qq->arr;

"dequeue" is declared to return type "int" but your returning "qq->arr" which is type "int*". Also, after you fix it (by deciding what you want to return--and stick with it, you shouldn't have to cast anything.).

		printf("%d ", qq->arr);

Again, same problem. Your telling "printf" to print an integer, but passing an "int*".

In "freeArr", you have a "{" when it should be a closing "}".

[Epy]

By the way, you don't compile header files.

[Dr Saucie]

Thanks ill fix my code and report back to let you know how things are going.

[Dr Saucie]

Why don't you compile headers?

[Epy]

They just get included, they aren't directly compiled. They contain type definitions and function prototypes for some other .c file. In any case, headers are taken care of simply by using #include. You don't need to supply them at the command-line.

[Dr Saucie]

ahhh ok, so i got all the errors corrected but i don't think im calling my queue methods correctly in my test. cause when i try to enqueue i get *** glibc detected *** ./a.out: free(): invalid pointer: 0x000000386241bbc0. and a bunch of other jargon

[nadroj]

I'd post all of your updated code. When changing from "int*"s to "int"s did you blindly make the change, or change the logic also?

[Dr Saucie]

test.c

#include <stdio.h>
#include <stdlib.h>
#include "queue.h"

int main()
{

	int choose = 0;
	int num;
	Queue q;

	printf("welcome to the queue ........\n");
	printf("1. enqueue\n");
	printf("2. dequeue\n");
	printf("3. print\n");
	printf("4. Check if queue is empty:\n");
	printf("5. get length\n");
	printf("6. free queue\n");
	printf("7. Exit\n");
	
	scanf("%d", &choose);

	switch(choose)
	{
		case 1:
			scanf("Enter a number to engueue: %d\n", &num);
			enqueue(&q, num);
		case 2:
			dequeue(&q);
		case 3:
			printArr(&q);
		case 4:
			empty(&q);
		case 5:
			length(&q);
		case 6:
			freeArr(&q);
		case 7: 
			break;
	}
return 0;
}

queue.c

#include <stdio.h>
#include <stdlib.h>
#include "queue.h"

void init ( Queue * qq)
{
	qq->cap = 26;
	qq->arr = malloc( sizeof(int) * qq->cap);
	qq->front = 0;
	qq->back = 0;
	qq->elements = 0;
 
}
void enqueue( Queue * qq, int num)
{
	if(qq->cap == qq->elements)
	{
		qq->arr = realloc(qq->arr, sizeof(int) * qq->cap);
		qq->arr[qq->back++] = num;
		qq->elements++;
	}
	else
	{
		qq->arr[ qq->back++ ] = num;
		qq->elements++;
	}
	
}

int dequeue( Queue * qq)
{
	int i;

	if(empty(qq))
	{
		printf("ITS EMPTY!!\n");
	}
	else
	{

		qq->elements--;
		qq->arr[qq->front] = 0;
		for(i=0; i<qq->elements; i++)
		{
			qq->arr[i] = qq->arr[i+1];
		}
	}
	return qq->arr[i];
}

int empty( Queue * qq)
{
	int test = 0;

	if(qq->arr == NULL)
	{
		test = 1;
	}
	return test;
}	

int length(Queue * qq)
{
	return qq->elements;
}

void printArr(Queue * qq)
{
	int i;
	
	for(i=0; i<qq->elements; i++)
	{
		printf("%d ", qq->arr[i]);
	} 
}

void freeArr( Queue * qq)
{
	if(qq != NULL)
	{
		free(qq->arr);
		free(qq);
	}
}

[nadroj]

Well you have an "init" function, to properly initialize all of the fields of a "Queue", but you never call it. Give that a shot.

[Dr Saucie]

ok lemme try that

[nadroj]

Also, in "freeArr", you're "free"ing "qq", which is not correct, since you never "malloc"ed it. Only free stuff that you malloc/realloc. Since its called "freeArr", it should only free the array!

[Dr Saucie]

is this what you ment?

int main()
{

	int choose = 0;
	int num;
	Queue q;
	init(&q);

	printf("welcome to the queue ........\n");
	printf("1. enqueue\n");
	printf("2. dequeue\n");
	printf("3. print\n");
	printf("4. Check if queue is empty\n");
	printf("5. get length\n");
	printf("6. free queue\n");
	printf("7. Exit\n");
	
	scanf("%d", &choose);

	switch(choose)
	{
		case 1:
			scanf("Enter a number to engueue: %d\n", &num);
			enqueue(&q, num);
		case 2:
			dequeue(&q);
		case 3:
			printArr(&q);
		case 4:
			empty(&q);
		case 5:
			length(&q);
		case 6:
			freeArr(&q);
		case 7: 
			break;
	}
return 0;
}

[Dr Saucie]

ok its not erroring out but i still have to fix some things, if i need some help ill be back. Thanks a lot!