我通过使用指针实现堆栈。它正在编译和工作,但是当堆栈为空时它不会下溢。它给了我一些垃圾价值。我认为这个问题是create_stack
函数中的问题。无论从堆栈中弹出多少数据都是奇怪的,我都不会收到段错误。堆栈由指针在C工作,除了在堆栈下溢
任何人都可以帮忙吗?
这里是我通过指针堆栈的完整实现。
#include<assert.h>
#include<stdio.h>
#include<stdlib.h>
enum action {PUSH = 1, POP, TOP, QUIT};
typedef struct node
{
int data;
struct node *lower;
}stack_node;
void clear_screen(void)
{
system("cls");
}
static enum action get_user_action(void)
{
int choice = 0;
do
{
clear_screen();
printf("%d Push data\n"
"%d Pop Data\n"
"%d See the top of the stack\n"
"%d Exit\n\n"
"Enter your choice -> ", PUSH, POP, TOP, QUIT);
scanf("%d", &choice);
} while (choice != PUSH && choice != POP && choice != TOP && choice != QUIT);
return (enum action) choice;
}
void create_stack(stack_node **top, int *status)
{
*top = malloc(sizeof(stack_node));
*status = PUSH - 1;
if (*top == NULL){
*status = PUSH;
}
}
void push(stack_node **top_stack, int *status, int data)
{
*status = PUSH - 1;
stack_node *node = malloc(sizeof(node));
if (node == NULL)
{
*status = PUSH;
return;
}
node -> data = data;
if (*top_stack == NULL){
node -> lower = NULL;
}
else{
node -> lower = *top_stack;
}
*top_stack = node;
}
int pop(stack_node **top_stack, int *status)
{
*status = PUSH - 1;
if (*top_stack == NULL){
*status = POP;
return -1;
}
stack_node *node = *top_stack;
int data = node -> data;
*top_stack = node -> lower;
free(node);
return data;
}
int see_top(stack_node **top_stack, int *status)
{
*status = PUSH - 1;
if (*top_stack == NULL){
*status = POP;
return -1;
}
return (*top_stack) -> data;
}
int main(void)
{
enum action choice;
int status;
stack_node *top = NULL;
create_stack(&top, &status);
if (status == PUSH)
{
printf("Not enough memory\n");
return 1;
}
while ((choice = get_user_action()) != QUIT)
{
clear_screen();
int data;
switch (choice)
{
case PUSH:
printf("Enter data to be pushed -> ");
scanf("%d", &data);
push(&top, &status, data);
if (status == PUSH){
printf("Not enough memory\n");
}
break;
case POP:
data = pop(&top, &status);
if (status == POP){
printf("Stack underflow\n");
}
else{
printf("The data is %d\n", data);
}
break;
case TOP:
data = see_top(&top, &status);
switch (status)
{
case POP:
printf("Nothing in the stack\n");
break;
default:
printf("The data at top is %d\n", data);
}
break;
default:
assert(!"You should not have reached this.");
}
getchar();
getchar();
}
}
为什么函数创建分配内存? –
@GrijeshChauhan因为我想做一个可重用的堆栈实现。我正在使用'指向指向struct的指针'来注意函数中分配的内存不会泄漏。分配的内存被放置在堆栈上。但正如我所说,我认真认为这个功能存在一个错误。它似乎正在凝视我的脸,但我不能放置它。 –
分配原因返回一个垃圾值,并在后续的弹出操作后,它可能是未定义行为的原因。 –