求后缀表达式 急急急

[avt_405]

#include<stdio.h>
#include<stdlib.h>
#define StackMaxSize 30

typedef int ElemType;
struct Stack
{
ElemType elem[StackMaxSize];
int top;
}s;

void Push(ElemType x)
{
if(s.top ==StackMaxSize - 1) //判断错误
printf("stack is full!\n");
else
s.elem[s.top++] = x; //
}

ElemType Pop()
{
ElemType e;
if(s.top == -1)
printf("stack is empty!\n");
else
e = s.elem[s.top--];
return e;
}

void ExprCompute(char *str)
{

char ch;
int i = 0, x;
ch = str[i++];
while(ch != '@')
{
switch(ch)
{
case '+':
x = Pop() + Pop();
break;
case '-':
x = Pop();
x = Pop() - x;
break;
case '*':
x = Pop() * Pop();
break;
case '/':
x = Pop();
if(x != 0)
x = Pop() / x;
else
{
printf("Divided by 0 !\n");
exit(1);
}
break;
case ' ':
ch=str[i++];
continue;
default:
x = ch - 48; //
break;
while(str[i] >= '0' && str[i] <= '9')
{
x = x * 10 + str[i] - 48; //
i++;
}
}
Push(x);
ch = str[i++];
}

if(s.top > -1)
{
x = Pop();
printf("%d",x);
if(s.top == -1)
return ;
else
{
printf("expression error !\n");
exit(1);
}
}
else
{
printf("Stack is empty!\n");
exit(1);
}
}
int
main()
{
s.top = -1;
char str[20];
printf("please input a string ended with a @:");
gets(str);

ExprCompute(str);

}
输入的时候数字和符号想用空格隔开 但是实现的有点问题 哪位大神给指点一下

[恨天低]

调试。

[avt_405]

跟没说不一样吗？混分不用这样吧，真的很着急

[石乐志123333]

哇！！40分啊！！！
我在你另一个帖子里回答了，希望给分啊
我也是新人

[JiMoKuangXiangQu]

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

#define StackMaxSize 30

typedef int ElemType;
struct Stack
{
	ElemType elem[StackMaxSize];
	int top;
}s;

void Push(ElemType x)
{
	if (s.top == -1) s.top = 0;

	if(s.top ==StackMaxSize - 1) //判断错误
		printf("stack is full!\n");
	else
		s.elem[s.top++] = x; //
}

ElemType Pop()
{
	ElemType e;
	if(s.top == -1)
		printf("stack is empty!\n");
	else
		e = s.elem[--s.top];
	return e;
}

void ExprCompute(char *str)
{
	char ch;
	int i = 0, x;
	ch = str[i++];
	while(ch != '@')
	{
		switch(ch)
		{
		case '+':
			x = Pop() + Pop();
			break;
		case '-':
			x = Pop();
			x = Pop() - x;
			break;
		case '*':
			x = Pop() * Pop();
			break;
		case '/':
			x = Pop();
			if(x != 0)
				x = Pop() / x;
			else
			{
				printf("Divided by 0 !\n");
				exit(1);
			}
			break;
		case ' ':
			ch=str[i++];
			continue;
		default:
			x = ch - 48; //
			break;
			while(str[i] >= '0' && str[i] <= '9')
			{
				x = x * 10 + str[i] - 48; //
				i++;
			}
		}
		Push(x);
		ch = str[i++];
	}

	if(s.top > -1)
	{
		x = Pop();
		printf("%d",x);
		if(s.top == -1)
			return ;
		else
		{
			printf("expression error !\n");
			exit(1);
		}
	}
	else
	{
		printf("Stack is empty!\n");
		exit(1);
	}
}

int
main()
{
	s.top = -1;
	char str[20];
	printf("please input a string ended with a @:");
	gets(str);

	ExprCompute(str);

	return 0;
}

s.top在第一次压栈时要正确初始化,出栈的时候应该用--s.top操作.
另外至少+操作有问题,应该再向后取一个操作数,而不是同时从栈上的出栈2个操作数.我没有修正这个问题.
其他的操作符应该也有问题.

学习调试是不可避免的,对自己有好处.