栈的链表实现出错

Question

我想做堆栈的链表实现，但是我的代码没有按预期工作。 我无法发现导致问题的原因，因此我将发布我的代码、当前输出和理想输出。 我不知道如何添加 n 是字母的 if 条件，然后执行 if 语句作为输入，如 no。 456 或执行else语句。 如果您解决了问题，请帮忙。

代码：

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


struct node{
    char data;
    struct node *next;
};

struct node*head;

void push(char x){
    if (head == NULL) {
        head= (struct node*) malloc(sizeof(struct node));
        head->data=x;
        head->next=NULL;
        printf("additon successful\n");        
        return ;
    }
    struct node *temp = (struct node*) malloc(sizeof(struct node));
    temp->next=head;
    temp->data=x;
    head=temp;
    printf("additon successful\n");  
    return ;
}

void pop(){
    if(head == NULL){
        printf("list is empty\n");
        return ;
}
struct node *temp = (struct node*) malloc(sizeof(struct node));
temp=head;
head=head->next;
free(temp);
printf("pop is successful\n");
return ;
}

void print(){
    struct node *temp = (struct node*) malloc(sizeof(struct node));
    temp=head;
    while(temp != NULL){
        printf("%c  ",temp->data);
        temp=temp->next;
    }
    printf("\nall items printed\n");
    return ;
}
void main() {
    char n;
    printf("enter alphabet\n");
    while (0!=1){
    scanf("%c",&n);
    if(n != 1 && n!= '`' && n!= 4 ) {
    push(n);}
    else if(n == 1) {
    pop();}
    else if(n == '`') {
    print();}
    else if(n == 4) {
    printf("\nexiting program");
    return ;}
    else {
    printf("enter valid argument\n");}
    }
}

输出：

enter alphabet
r
additon successful             // why is this printing twice?
additon successful
a
additon successful
additon successful
n
additon successful
additon successful
d
additon successful
additon successful
1                               // for 1 code should perform pop operation
additon successful
additon successful
4                               // for 4 function should end        
additon successful
additon successful
456                             // i could not figure how to add  in if condition that n is 
                                   aplphabet then execute if statement for such no. like 456 
                                   execute else 
additon successful
additon successful
additon successful              //why so many executions?
additon successful

理想输出：

1
list is empty
r
additon successful
e
additon successful
a
additon successful
d
additon successful
1
pop is successful
1
pop is successful
`
a  d
all items printed
456
enter valid argument
4
exiting program

Answer 1

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


struct node{
    char data;
    struct node *next;
};

struct node*head;

void push(char x){
    if (head == NULL) {
        head= (struct node*) malloc(sizeof(struct node));
        head->data=x;
        head->next=NULL;
        printf("additon successful\n");        
        return ;
    }
    struct node *temp = (struct node*) malloc(sizeof(struct node));
    temp->next=head;
    temp->data=x;
    head=temp;
    printf("additon successful\n");  
    return ;
}

void pop(){
    if(head == NULL){
        printf("list is empty\n");
        return ;
}
struct node *temp;
temp=head;
head=head->next;
free(temp);
printf("pop is successful\n");
return ;
}

void print(){
    struct node *temp;
    temp=head;
    while(temp != NULL){
        printf("%c  ",temp->data);
        temp=temp->next;
    }
    printf("\nall items printed\n");
    return ;
}
int main() {
    char n;
    printf("enter alphabet\n");
    while (0!=1){
    scanf(" %c",&n);
    if(isalpha(n)) {
    push(n);}
    else if(n == '1') {
    pop();}
    else if(n == '`') {
    print();}
    else if(n == '4') {
    printf("\nexiting program");
    return 0;}
    else {
    printf("enter valid argument\n");}
    }
}

最终解决方案