c++ - 打印堆栈的元素

Question

我的代码

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

struct node {
    char ch;
    struct node *next;
};
struct node *first,*top1,*newptr;

void push_back(char data) { //Pushes data into the stack
    if (first == NULL) {
        first = new node();
        first->next = NULL;
        first->ch = data;
    }

    else {
        first = new node();
        top1->next = first;
        top1->ch = data;
        first = top1;
    }
}

void display() {
    top1 = first;

    if (top1 == NULL){
        printf("Stack is empty");
        return;
    }

    while (top1 != NULL){
        printf("%c ", top1->ch);
        top1 = top1->next;
    }
}


main() {
    first = NULL;
    char EXP[100];

    scanf("%s",&EXP);
    system("cls");
    int len = strlen(EXP);

    for(int i=0;i<len;i++)
        push_back(EXP[i]);

    display();

    system("pause");
}

我的程序应该为用户获取一个字符串，然后将每个字符放入一个堆栈中，然后我会打印回该字符串。当我运行我的代码时，它只能显示第一个字符。我错过了什么吗？

Answer 1

当你第二次 push_back() 时，你会立即覆盖 first

else {
    first = new node();    //oops
    top1->next = first;
    top1->ch = data;
    first = top1;

丢失它之前指向的数据。