#include<stdio.h>
#include<stdlib.h>
#define OK 1
#define ERROR 0
#define STACKINCREMENT 5
#define STACK_INIT_SIZE 10
typedef char SElemType;
typedef int Status;
typedef struct{
SElemType *base;//栈底指针
SElemType *top;//栈顶指针
int stacksize;//当前已经分配的存储空间
}SqStack;
char precede[7][7]={
{'>','>','<','<','<','>','>'},
{'>','>','<','<','<','>','>'},
{'>','>','>','>','<','>','>'},
{'>','>','>','>','<','>','>'},
{'<','<','<','<','<','=','!'},
{'>','>','>','>','!','>','>'},
{'<','<','<','<','<','!','='}
};//定义算符之间优先关系的二维数组
//构造一个存放char型数据的空栈
Status InitStack(SqStack *s){
s->base = (SElemType *)malloc(STACK_INIT_SIZE*sizeof(SElemType));
if(!s->base) return ERROR;
s->top = s->base;//栈中元素个数为0
s->stacksize = STACK_INIT_SIZE;
return OK;
}
//入栈
Status Push(SqStack *s,SElemType e){
if(s->top-s->base>=s->stacksize){
s->base = (SElemType *)realloc(s->base,(STACKINCREMENT+s->stacksize)*sizeof(SElemType));
if(!s->base) exit(0);
s->top = s->base+s->stacksize;
s->stacksize += STACKINCREMENT;
}
*s->top++ = e;
return OK;
}
//出栈
Status Pop(SqStack *s,SElemType *e)
{
if(s->base==s->top){
printf("空栈！\n");
return ERROR;
}
*e = *--s->top;
return OK;
}
//得到栈顶元素
SElemType GetTop(SqStack *s){
return *(s->top-1);
}
//确定输入的字符如果是操作符的话判断在二维数组中的下标 若是数字的话就另外与操作符区分开 便于在输入表达式时是入哪个栈
int Index(char c){
switch(c){
case '+': return 0;
case '-': return 1;
case '*': return 2;
case '/': return 3;
case '(': return 4;
case ')': return 5;
case '#': return 6;
default: return 7;
}
}
//判断优先级,返回大小 < > = !
char Priority(char a,char b){
int x,y;
x = Index(a); y = Index(b);
if(x!=7&&y!=7)
return precede[x][y];
else
return '!';
}
//简单表达式求值
double Operate(double a,char theta,double b){
switch(theta){
case '+': return a + b;
case '-': return a - b;
case '*': return a * b;
case '/': return a / b;
}
}
//判断是字符是否是数字
Status isdigit(char ch){
if(ch>='0'&&ch<='9') return OK;
return ERROR;
}
//算术表达式求值
Status PrintStack1(SqStack S,int &m)
//若栈S不空则从栈底到栈顶输出S的元素(为char型)并返回打印长度
{
m=0;
char *p;
if(S.base==S.top) return ERROR;
for(p=S.base;p!=S.top;p++)
{ printf("'%c'",*p); m++;}
return OK;
}//PrintStack1
Status PrintStack2(SqStack S,int &n)
//若栈S不空则从栈底到栈顶输出S的元素(为char型)并返回打印长度
{
n=0;
char *p;
if(S.base==S.top) return ERROR;
for(p=S.base;p!=S.top;p++)
{ printf("'%d'",*p); n++;}
return OK;
}//PrintStack1
int GetExpressionValue(){
int m,n,i=0;
SqStack OPTR,OPND;
SElemType result;//返回最后结果
InitStack(&OPTR);
InitStack(&OPND);
Push(&OPTR,'#');//将结束符置于操作符的底端
printf("请输入算术表达式(以#结尾,负数用括号括起来）:\n");
char c = getchar();
printf("步骤\tOPTR栈\t\tOPND栈\t\t当前字符 主要操作\n");
while(c!='#'||GetTop(&OPTR)!='#'){//当*c=='#'&&栈顶字符=='#'的时候
i++;
printf(" %d\t",i);//打印序号
PrintStack1(OPTR,m);putchar('\t');//打印OPTR栈
if(m<10) putchar('\t');//若打印长度不够8要再
PrintStack2(OPND,n);putchar('\t');//打印OPND栈
if(n<10) putchar('\t');
if(isdigit(c)){//如果是数字的话将其转化为数字 然后入操作数栈
int data[10];
int i,num;
i = num =0;//num是一个中间数 用于将字符串中的数字转化为整数然后入栈 i是用于将字符串中的字符存入data数组
while(isdigit(c)){
data[i] = c-'0';
i++;
c = getchar();
}
for(int j=0;j<i;j++){
num = num*10+data[j];
}
printf(" %d\t ",num);//打印当前字符
printf("Push2(OPND,%d)\n",num);//打印该操作
Push(&OPND,num);
}else{//如果是字符的话将其入操作符栈
SElemType a,b,theta;//a b theta是用来返回操作数栈和操作符栈里的元素的
switch(Priority(GetTop(&OPTR),c)){//比较即将入栈的字符与栈顶 操作符的优先级关系
case '<':Push(&OPTR,c);
printf(" %c\t ",c);//打印当前字符
printf("Push1(OPND,%c)\n",c);//打印该操作
c = getchar();
break;
case '>':Pop(&OPND,&b);
Pop(&OPND,&a);
Pop(&OPTR,&theta);
Push(&OPND,Operate(a,theta,b));
printf(" %c\t ",c);//打印当前字符
printf("Operate(%d,'%c',%d)\n",a,theta,b);//打印该操作
break;//将结果入栈
case '=':Pop(&OPTR,&theta);
c = getchar();
break;//说明括号相遇 删除栈内括号即可
default:break;
}
}
}
Pop(&OPND,&result);
printf("结果是：%d",result);
}
int main(){
GetExpressionValue();
return 0;
}
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