对实现堆栈的怀疑 [英] DOUBT ON IMPLEMENTATION OF STACK

问题描述

当我运行编译好的文件时，它会显示分段错误.
这有什么不对?
请帮助！！！

WHEN I RUN THE COMPILED FILE ITS SHOWING SEGMENTATION FAULT.
WHAT''S WRONG WITH THIS?
PLEASE HELP!!!

#include<stdio.h>
#include<malloc.h>
struct node{
	int data;
	struct node *link;
	}*top,*ptr,*start;
main()
{	
	top->link=NULL;
	int choice,info;
	printf("CHOOSE AN OPTION\n");
	scanf("%d",&choice);
	printf("1.PUSH AN ELEMENT\n");
	printf("2.POP AN ELEMENT\n");
	printf("3.DISPLAY\n");
	printf("4.EXIT\n");
	switch(choice)
	{
		case 1:
		printf("ENTER THE ELEMENT YOU WANT TO PUSH\n");
		scanf("%d",&info);
		push(info);
		break;
		/*case 2:
		pop(top->data);
		break;*/
		case 3:
		display();
		break;
	}
}
push(int info)
{	
	if(top->link!=NULL)
	{
		ptr->link=top;
		top=malloc(sizeof(struct node));
		top->data=info;
		top->link=NULL;
	}
	else
	{
	start->link=top;
	top->data=info;
	top->link=NULL;
	}
	
}

display()
{	ptr=start;
	while(ptr->link!=NULL)
	{	
		int info;
		info=(ptr->data);
		printf("%d\t",info);
		ptr=ptr->link;
	}
}

当我运行编译好的文件时，它会显示分段错误.
这有什么不对?
请帮助!!!

WHEN I RUN THE COMPILED FILE ITS SHOWING SEGMENTATION FAULT.
WHAT''S WRONG WITH THIS?
PLEASE HELP!!!

推荐答案

请看main的第一行. top来自哪里?您从未为该指针分配内存.

—SA

Look at the very first line of main. Where top comes from? You never allocated memory for this pointer.

—SA

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