#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
typedef char DataType;
#define _capacity 100// 底层空间的总大小
typedef struct Stack
{
DataType _array[_capacity];
int _top; // 表示有效元素个数 表示栈顶位置
}Stack;
//初始化
void StackInit(Stack* s)
{
s->_top = 0;
}
// 入栈
void StackPush(Stack* s, DataType data)
{
if (s->_top ==_capacity )
{
printf(“栈满！！！”);
}
s->_array[s->_top++] = data;
}
// 出栈
void StackPop(Stack* s)
{
if (s->_top == 0)
{
printf(“栈为空！！！”);
return;
}
s->_top–;
}
// 获取栈顶元素
DataType StackTop(Stack* s)
{
if (s->_top == 0)
{
printf(“栈为空！！！”);
return 0;
}
DataType x = s->_array[s->_top-1];
return x;
}
// 有效元素的个数
int StackSize(Stack* s)
{
return s->_top;
}
// 检测栈是否为空
int StackEmpty(Stack* s)
{
if (s->_top == 0)
return 1;
return 0;
}
//打印
void printstack(Stack * s)
{
if (s->_top == 0)
{
printf(“栈为空！！！”);
}
while (s->_top)
{
printf(“%d “, s->_array[–s->_top]);
}
}
// 栈的应用
//2. 用栈解决括号匹配问题，测试用例见课件、
int lookupbracket(Stack *s, char *str)
{
// { [ ( ) ] }
while (*str != ‘\0’)
{
char c = *str;
switch (c)
{
case ‘(‘:
{
StackPush(s, c);
break;
}
case ‘{‘:
{
StackPush(s, c);
break;
}
case ‘[‘:
{
StackPush(s, c);
break;
}
case ‘)’:
{
if (StackTop(s) == ‘(‘)
{
StackPop(s);
}
break;
}
case ‘}’:
{
if (StackTop(s) == ‘{‘)
{
StackPop(s);
}
break;
}
case ‘]’:
{
if (StackTop(s) == ‘[‘)
{
StackPop(s);
}
break;
}
}
str++;
}
return s->_top;
}
//3. 用栈求解后缀表达式值
int suffix_expression(Stack *s, char *str)
{
// 15\4\5\*\+
assert(str);
int tmp1 = 0;
int tmp2 = 0;
int num = 0;
while (*str != ‘\0’)
{
char c = *str;
if (c >= ‘0’&&c <= ‘9’)
{
StackPush(s,c – ‘0’);
}
else if (c == ‘+’)
{
tmp1=StackTop(s);
StackPop(s);
tmp2 = StackTop(s);
StackPop(s);
num = tmp1+tmp2;
StackPush(s, num);
}
else if (c == ‘-‘)
{
tmp1 = StackTop(s);
StackPop(s);
tmp2 = StackTop(s);
StackPop(s);
num = tmp1-tmp2;
StackPush(s, num);
}
else if (c == ‘*’)
{
tmp1 = StackTop(s);
StackPop(s);
tmp2 = StackTop(s);
StackPop(s);
num = tmp1*tmp2;
StackPush(s, num);
}
else if (c == ‘/’)
{
tmp1 = StackTop(s);
StackPop(s);
tmp2 = StackTop(s);
StackPop(s);
num = tmp1/tmp2;
StackPush(s, num);
}
str++;
}
return StackTop(s);
}
int main()
{
Stack s;
char str[7] = “15\4\5\*\+”;
StackInit(&s);
printf(“%d”, suffix_expression(&s, str));
system(“pause”);
return 0;
}
