Question

求大神帮忙看看这个C语言程序哪里错了 本人新手 看不出来 谢谢

#include "stdio.h"
#include "string.h"
#include "malloc.h"
#include "stdlib.h"
#define INIT 100
#define DECREAT 10
#define LEN sizeof(char)
#define NULL 0
typedef struct
{
char *base;
char *top;
int size;
}Stack;
void init(Stack *p)
{
p->base = (char *)malloc(INIT *LEN);
if(!p->base)
exit(1);
p->top = p->base;
p->size = INIT;
}
char getTop(Stack *p,char a)
{
if(p->base == p->top)
return NULL;
a = *(p->top - 1);
return a;
}
void Push(Stack *p,char a)
{
if(p->top - p->base >= p->size)
{
p->base = (char *)realloc(p->base,LEN * (p->size + DECREAT));
if(p->base == 0)
printf("failed!");
p->top = p->base + p->size;
p->size += DECREAT;
}
*p->top++ = a;
}
char Pop(Stack *p,char a)
{
if(p->top == p->base)
printf("null");
a = *--p->top;
}
main()
{
Stack *p;
char x,a,b;
int i = 1;
init(p);
while((x=getchar()) != '$')
Push(p,x);
b = getTop(p,a);
printf("%c",b);
b = Pop(p,a);
printf("%c",b);
}

Answer 1

#define NULL 0  这个系统给了，不用定义

下面加一句

char getTop(Stack *p,char a)

{

    if(p->base == p->top)

        return NULL;

    a = *p->top - 1;

    return a;

}

#include "stdio.h"
#include "string.h"
#include "malloc.h"
#include "stdlib.h"
#define INIT 100
#define DECREAT 10
#define LEN sizeof(char)
typedef struct
{
    char *base;
    char *top;
    int size;
}Stack;
void init(Stack *p)
{
    p->base = (char *)malloc(INIT *LEN);
    if(!p->base)
        exit(1);
    p->top = p->base;
    p->size = INIT;
}
char getTop(Stack *p,char a)
{
    if(p->base == p->top)
        return (char)NULL;   //这个NULL是整型，不能转成char...
    a = *p->top - 1;
    return a;
}
void Push(Stack *p,char a)
{
    if(p->top - p->base >= p->size)
    {
        p->base = (char *)realloc(p->base,LEN * (p->size + DECREAT));
        if(p->base == 0)
            printf("failed!");
        p->top = p->base + p->size;
        p->size += DECREAT;
    }
    *p->top++ = a;
}
char Pop(Stack *p,char a)
{
    if(p->top == p->base)
        printf("null");
    a = *--p->top;
    return a;
}
main()
{
    Stack *p;     
    char x,a,b;         //这里的a与上面的p没有赋值
    int i = 1;
    init(p);
    while((x=getchar()) != '$')
       Push(p,x);
    b = getTop(p,a);
    printf("%c",b);
    b = Pop(p,a);
    printf("%c",b);
}

追问

大神能否给发下个直接修改好的?

追答

什么功能？