#include<stdio.h>#include<stdlib.h>#define OK 1#define ERROR 0#define STACKINCREMENT 5#define STACK_INIT_SIZE 10typedef 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;}//PrintStack1Status 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;}//PrintStack1int 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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