算数表达式求值

首先输入要测试的组数；然后在输入要计算的算数表达式；比如：8*6+6/3*(5+6*5)=代码如下：#include <stdio.h>#include <stdlib.h>#include <string.h>#define MAXSIZE 100int ans[7][7]={2,2,1,1,1,2,2,2,2,1,1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1,2,2,1,1,1,1,1,3,0,2,2,2,2,0,2,2,1,1,1,1,1,0,3};typedef float ElemType;typedef struct stack{ElemType data[MAXSIZE];int top;}seqstack;typedef struct{char ch[MAXSIZE];int length;}stack;stack *inits(){stack *s=(stack *)malloc(sizeof(stack));s->length=-1;return s;}//初始化seqstack *init(){seqstack *s=(seqstack *)malloc(sizeof(seqstack)); s->top=-1;return s;}//入栈int pushs(stack *s,char x){if(s->length==MAXSIZE-1){printf("The stack is overflow!\n");return 0;}s->length++;s->ch[s->length]=x;return 1;}int push(seqstack *s,ElemType x){if(s->top==MAXSIZE-1){printf("The stack is overflow!\n"); return 0;}s->top++;s->data[s->top]=x;return 1;}//出栈int pops(stack *s){if(s->length==-1){printf("The stack is underflow!\n"); return 0;}printf("%c",s->ch[s->length]);s->length--;return 1;}int pop(seqstack *s){if(s->top==-1){printf("The stack is underflow!\n"); return 0;}printf("%.2f ",s->data[s->top]);s->top--;return 1;}//取栈顶元char gettops(stack *s){return s->ch[s->length];}ElemType gettop(seqstack *s) {return s->data[s->top]; }char precede(char c1,char c2) {int i,j,n;switch(c1){case '+': i=0;break; case '-': i=1;break; case '*': i=2;break; case '/': i=3;break; case '(': i=4;break; case ')': i=5;break; case '=': i=6;break; }switch(c2){case '+': j=0;break; case '-': j=1;break; case '*': j=2;break; case '/': j=3;break; case '(': j=4;break; case ')': j=5;break; case '=': j=6;break; }n=ans[i][j];switch(n){case 1:return '<';case 2:return '>';case 3:return '=';default :printf("输入错误！"); break;}}int lsop(char c){switch(c){case '+':return 1;case '-':return 1;case '*':return 1;case '/':return 1;case '=':return 1;case '(':return 1;case ')':return 1;case '.':return 2;default:return 0;}}float Operate(float a, char theta, float b) {float res = 0.0;switch (theta){case '+':res = a + b;break;case '-':res = a - b;break;case '*':res = a * b;break;case '/':res = a / b;break;default:break;}return res;}int main(){int q,l;printf("请输入式子并以'='结束\n");printf("比如:3.25*40/7+6*(50/2–3)=\n"); printf("请输入你要测试的组数:");scanf("%d",&q);for(l=0;l<q;l++){int c,n,i,j,r,m,o;float sum,sum1,h,a,b;float p=0.1;char f,theta,y;int counter=0;seqstack *s1=init();seqstack *s3;stack *s2=inits();stack *s4;s2->ch[0]='=';s2->length++;scanf(" %c",&f);while(f!='='||gettops(s2)!='='){sum=0;sum1=0;c=lsop(f);if(lsop(f)==0){if(counter==1){double t=gettop(s1); s1->top--;push(s1,t*10+(f-'0')); counter=1;}else if(counter==2){double q=gettop(s1); s1->top--;push(s1,(f-'0')*p+q); p=p*0.1;counter=2;}else{push(s1,f-'0');counter++;}scanf(" %c",&f);}if(lsop(f)==2){scanf(" %c",&f);counter=2;}if(lsop(f)==1){counter=0;p=0.1;y=precede(gettops(s2),f);switch(y){case '<':{pushs(s2,f);scanf(" %c",&f);break;}case '=':{s2->length--;scanf(" %c",&f);break;}case '>':{theta = gettops(s2);s2->length--;a = gettop(s1);s1->top--;b = gettop(s1);s1->top--;push(s1,Operate(b,theta,a)); }}}}printf("结果是:");while(s1->top!=-1)pop(s1);printf("\n");}return 0;}。