###### 问题遇到的现象和发生背景
###### 问题相关代码，请勿粘贴截图
###### 运行结果及报错内容
###### 我的解答思路和尝试过的方法
###### 我想要达到的结果
#include <iostream>
#include <stdbool.h>
#include <string.h>
#include <malloc.h>
#define MAX_CAPTURE 20
using namespace std;
typedef struct line_stack
{
int cnt;//栈有效元素个数
int cap;//栈最大容量
char *pBottom;//栈底//指向数组第一个元素的指针
}STACK,*PSTACK;
void initial(PSTACK SL);
bool empty_stack(PSTACK SL);
void destory(PSTACK SL);
void clear_stack(PSTACK SL);
int length_of_stack(PSTACK SL);
void push_stack(PSTACK SL,char ch);
bool pop_stack(PSTACK SL,char *s);//弹出一个字符串，第一个元素即为需要的元素
bool GetTop(PSTACK SL,char *s);
void traverse(PSTACK SL);
bool in(char c);
char precede(char a,char b);
char EvalueateExpression();
int main()
{
/*STACK SL;
char s[5];
initial(&SL);
push_stack(&SL,'a');
push_stack(&SL,'y');
push_stack(&SL,'s');
traverse(&SL);
if(empty_stack(&SL))
cout << "栈空" << endl;
else
cout <<"栈不空" << endl;
cout << "栈长度为：" << length_of_stack(&SL) << endl;
pop_stack(&SL,s);
cout << "弹出的元素为:" << s <<endl;
cout << "栈长度为：" << length_of_stack(&SL) << endl;
traverse(&SL);*/
cout << "输入一个表达式（结果在-127-128之间|中间数在0-9之间）： ";
cout << EvalueateExpression() <<endl;
return 0;
}
void initial(PSTACK SL)
{
SL->pBottom = (char*)malloc(sizeof(char)*SL->cap);
if(!SL->pBottom)
{
cout << "动态分配内存失败！" << endl;
exit(-1);
}
SL->cnt = 0;
SL->cap = MAX_CAPTURE;
//cout << "初始化成功！" << endl;
}
bool empty_stack(PSTACK SL)
{
if(SL->cnt == 0)
return true;
else
return false;
}
void destory(PSTACK SL)
{
free(SL->pBottom);
SL->pBottom = NULL;
SL->cnt = 0;
}
void clear_stack(PSTACK SL)
{
while(SL->cnt != 0)
SL->pBottom[SL->cnt-1] = '\0';
}
int length_of_stack(PSTACK SL)
{
int i = 0;
if(empty_stack(SL))
return i;
else
{
return SL->cnt;
}
}
void push_stack(PSTACK SL,char ch)
{
if(SL->cnt == SL->cap)
{
SL->pBottom = (char*)realloc(SL->pBottom,(sizeof(char)*(SL->cap + 2)));
if(!SL->pBottom)
{
cout << "追加内存失败" << endl;
exit(-1);
}
else
{
SL->cnt += 2;
}
}
SL->pBottom[SL->cnt] = ch;
SL->cnt++;
//SL->pBottom[SL->cnt] = '\0';
}
bool pop_stack(PSTACK SL,char *s)
{
if(empty_stack(SL))
{
cout << "栈空，无元素可弹出" << endl;
return false;
}
else
{
s[0] = SL->pBottom[(SL->cnt)-1];
SL->cnt--;
return true;
}
}
bool GetTop(PSTACK SL,char *s)
{
if(!empty_stack(SL))
{
s[0] = SL->pBottom[(SL->cnt)-1];
return true;
}
else
{
cout << "栈空，无法GETTOP" << endl;
return false;
}
}
void traverse(PSTACK SL)
{
if(empty_stack(SL))
cout << "栈空，无法遍历" << endl;
else
{
int i = SL->cnt;
cout << "栈内元素有：";
while(i > 0)
{
cout << SL->pBottom[i-1] << " ";
--i;
}
cout << endl;
}
}
bool in(char c)
{
if(c == '+' || c == '-' || c == '*' || c == '/' || c == '(' || c == ')'|| c == '\n')
return true;
else
return false;
}
char operate(char c1,char tha, char c2)
//注意c1\c2顺序要与表达式一致
{
switch(tha)
{
case '+':return c1+c2;
case '-':return c1-c2;
case '*':return c1*c2;
}
return c1/c2;
}//为啥÷要放在选择结构外面？？
char precede(char a,char b)
{
char f;
switch(b)
{
case '+':
case '-':if(a == '(' || a == '\n')
f = '<';
else
f = '>';
break;
case '*':
case '/':if(a == ')'|| a == '*' || a == '/')
f = '>';
else
f = '<';
break;
case '(':if(a == ')')
{
cout << "括号不符合规则！" << endl;
exit(-1);
}
else
f = '<';
break;
case ')':switch(a)
{
case '(':f = '=';
break;
case '\n':
{
cout << "缺失左括号" << endl;
exit(-1);
}
default:f = '>';
}
//break;
case '\n':switch(a)
{
case '(':
{
cout << "缺失右括号" << endl;
exit(-1);
}
case '\n':f = '=';
break;
default: f = '>';
}
}
return f;
}
char EvalueateExpression()
{
PSTACK OPND,OPTR;
initial(OPND);
initial(OPTR);
push_stack(OPTR,'\n');
char c,x,a,b;
char s[5];
c = getchar();
GetTop(OPTR,s);
x = s[0];
while (c != '\n' || x != '\n')
{
if(in(c))
{
switch(precede(x,c))
{
case '>':
push_stack(OPTR,c);
c =getchar();
break;
case '=':
pop_stack(OPTR,s);
c = getchar();
break;
case '<':
pop_stack(OPTR,s);
x = s[0];
pop_stack(OPND,s);
b = s[0];
pop_stack(OPND,s);
a = s[0];
push_stack(OPND,operate(a,x,b));
}
}
else if(c >= '0' && c <= '9')
{
push_stack(OPND,c- '0');
c = getchar();
}
else
{
cout << "出现非法字符！" << endl;
exit(-1);
}
GetTop(OPTR,s);
x = s[0];
}
pop_stack(OPND,s);
x = s[0];
if(!empty_stack(OPND))
{
cout << "表达式有问题！" << endl;
exit(-1);
}
return x;
}
