Need Help: Stack ADT Linked list with VOID STAR implementation (C Programming)
First of all, i couldn't use "code sample" therefore i am adding my codes as stated below:
Header.h
#ifndef MYHEADER_H
#define MYHEADER_H
#define EMPTY_TOS -1
#define MIN_STACK_SIZE 5
#define FALSE 0
#define TRUE 1
struct Node;
typedef struct Node *Stack;
void *PopStack(Stack);
void *TopOfStack(Stack);
void PushStack(void *val, Stack);
int IsEmptyStack(Stack);
int IsFullStack(Stack);
#endif
Header.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "myheader.h"
#define EMPTY_TOS -1
#define MIN_STACK_SIZE 5
#define FALSE 0
#define TRUE 1
struct Node
{
void *val;
struct Node *next;
};
void PushStack(void *x, Stack s)
{
printf("/n a1");
struct Node *insert;
printf("/n a2");
inser开发者_Go百科t = (struct Node *) malloc(sizeof(struct Node));
printf("/n a3");
if (insert == NULL)
printf("Out of memory space!\n");
else
{ printf("\n a4");
insert->val = x;printf("\n a5");
insert->next= s;printf("\n a6");
s = insert;printf("\n a7");
}
printf("\n a8");
}
void *PopStack(Stack s)
{ printf("\n pop1");
struct Node *remove; printf("\n pop2");
void *val; printf("\n pop3");
if (IsEmptyStack(s))
{
printf("\nThe stack is empty!\n");
}
else
{ printf("\n pop4");
remove = s; printf("\n pop5");
val = remove->val; printf("\n pop67");
s = s->next; printf("\n pop7");
free(remove); printf("\n pop8");
}
return val; printf("\n pop9");
}
void *TopOfStack(Stack s)
{
if (!IsEmptyStack(s))
return s->next->val;
else
{
printf("\nThe stack is empty\n");
return 0;
}
}
int IsEmptyStack(Stack s)
{
printf("empty");
return (s == NULL);
}
int IsFullStack(Stack s)
{
return FALSE;
}
Project.cpp
int main()
{
Stack S = NULL;
int x = 5;
PushStack((void *)x, S);
int z = (int)PopStack(S);
printf("\n z = %d \n", z);
system("PAUSE");
return 0;
}
EDIT: I want to put X, into S(tack) by using PushStack function. And then i want to take the value(5) stored in S and print it as Z which is an integer. But i see a numbers like 4247612, which does not change as long as the compiler window is not closed.
Note that PushStack((void *)x, S); int z = (int)PopStack(S);
can incur truncation, and so, puncasting types like this is not guaranteed to work in all cases: void *
is not a magic type that can hold each and every possible value in the universe. (It would especially go up in flames if you started to use double
s instead of int
s on contemporary implementations.) It may however point to one.
The problem is that you've defined Stack
as a struct Node *
and are trying to update its value inside the PushStack()
and PopStack()
functions. When you assign a value to s
inside either function, it only updates the local variable, and not S
in your main function. Instead, PushStack()
and PopStack()
may need to take a pointer to a stack object (Stack *
) so that you can update the caller's value too.
Your PushStack
and PopStack
routines is not doing what you want
To exhibit it explicitly in the PopStack
function:
void *PopStack(Stack s) { // <-- The s declared here is a LOCAL copy of the s your pass
struct Node *remove;
void *val;
if (IsEmptyStack(s)) {
printf("\nThe stack is empty!\n");
} else {
remove = s;
val = remove->val;
s = s->next; // <-- Changes the local copy, but the original is unchanged
free(remove);
}
return val;
}
Because the S
in main is never updated it continues to be NULL.
You would fix this by passing a Stack *s
, and accessing it using *s
in both function.
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