在C中使用链接列表实现堆栈 [英] implementing stack with linked list in C

问题描述

我在使用带有struct的链表实现Stack时遇到麻烦.该程序编译良好，但是当我运行它时，它会打印第一个元素，但随后将下一个节点读取为NULL.我认为将堆栈传递给push方法可能是错误的，但是我不确定，并且修复失败，因此我寻求您的帮助:

I'm having trouble implementing a Stack using a linked list with struct. The program compiles fine but when I run it, it prints the first element but then reads the next node as a NULL. I think it might be an error with my passing of the stack to the push method but I am not sure and I have not been successful in fixing it so I'm asking for your help:

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

struct stackNode{
    char data;
    struct stackNode *nextPtr;
};
typedef struct stackNode StackNode;
typedef StackNode *StackNodePtr;

void convertToPostfix(char infix[], char postfix[]);
int isOperator(char c);
int precedence(char operator1, char operator2);
void push(StackNodePtr *topPtr, char value);
char pop(StackNodePtr *topPtr);
char stackTop(StackNodePtr topPtr);
int isEmpty(StackNodePtr topPtr);
void printStack(StackNodePtr topPtr);

int main(){
    convertToPostfix(NULL, NULL);
    return 0;
}

void convertToPostfix(char infix[], char postfix[]){
    StackNode stack = {'(', NULL};
    StackNodePtr stackPtr = &stack;
    push(stackPtr, 'a');

    //printf("%s\n", stackPtr->data);
    printStack(&stack);
}

void push(StackNodePtr *topPtr, char value){
        StackNode *node;
        node=(StackNodePtr)malloc(sizeof(StackNodePtr));

        node->data=value;
        node->nextPtr=*topPtr;
        *topPtr=node;
}

void printStack(StackNodePtr topPtr){
    if(topPtr == NULL){
        printf("%s\n", "NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO");
        return;
    }

    printf("%c\n", topPtr->data);
    printStack(topPtr->nextPtr);
}

任何帮助将不胜感激.

谢谢

推荐答案

我可以看到几个问题:

1)当您将stackPtr的地址传递给push函数时，printStack(&stack);应该为printStack(stackPtr);.

1) printStack(&stack); should be printStack(stackPtr); as you are passing address of stackPtr to the push function.

2)

node = (StackNodePtr)malloc(sizeof(StackNodePtr));

应为:

node = malloc(sizeof(StackNode));

3)

push(stackPtr, 'a');

应为:

push(&stackPtr, 'a');

您需要传递顶部指针的地址.

As you need to pass the address of the top pointer.

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