请教下判断栈为空的函数怎么写？

Question

#define maxnum 20#include<stdio.h>#include<stdlib.h>struct stacktype{int stack[maxnum];int top;};int push(struct stacktype *s,int x){if(s->top>=maxnum-1)return false;elses->top++;s->stack[s->top]=x;return true;}int pop(struct stacktype *s){if(s->top <0)return NULL;elses->top--;return(s->stack[s->top+1]);}dec_to_bin(int n,int b){int e;InitStack(S);//请问初始化堆栈函数怎么写？while(n){push(S,n%b);n=n/b;}while(!StackEmpty)//判断栈为空的函数怎么写？{e=pop(S);printf("%d",e);}}main{dec_to_bin(13,2);}

Answer 1

我帮你写了InitStack和StackEmpty函数，程序最终结果如下：
#define maxnum 20
#include<stdio.h>
#include<stdlib.h>

struct stacktype
{
int stack[maxnum];
int top;
};
struct stacktype *S;//顶一个堆栈
int push(struct stacktype *s,int x)
{
if(s->top>=maxnum-1)
return false;
else
s->top++;
s->stack[s->top]=x;
return true;
}

int pop(struct stacktype *s)
{
if(s->top <0)
return NULL;
else
s->top--;
return(s->stack[s->top+1]);
}
//初始化堆栈
void InitStack(struct stacktype* &S)
{
S = (struct stacktype *)malloc(sizeof(struct stacktype));
S->top = -1;
}
//判断堆栈是否为空
bool StackEmpty(struct stacktype *S)
{
if (S->top <0)
{
return true;
}
return false;
}

void dec_to_bin(int n,int b)
{
int e;

InitStack(S);//请问初始化堆栈函数怎么写？
if (S ==NULL)
{
printf("error \n");
return;
}
while(n)
{
push(S,n%b);
n=n/b;
}
while(!StackEmpty(S))//判断栈为空的函数怎么写？
{
e=pop(S);
printf("%d",e);
}
}

void main()
{
dec_to_bin(13,2);
printf("\n");
}
程序运行结果为：
1101