expevaluation.c

This program use for ExpEvaluation

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "stack.c"
#include "stackdouble.c"
#define Max 100         /* operand's longest digit */
#define TRUE 1
#define FALSE 0 
#define NUMOFOPR 7        /* Number of operator */
static char OPS[NUMOFOPR]={'+','-','*','/','(',')','#'};
static char order[NUMOFOPR][NUMOFOPR]={
{'>','>','<','<','<','>','>'},
{'>','>','<','<','<','>','>'},
{'>','>','>','>','<','>','>'},
{'>','>','>','>','<','>','>'},
{'<','<','<','<','<','=',' '},
{'>','>','>','>',' ','>','>'},
{'<','<','<','<','<',' ','='}
};

float Execute(float a,char op, float b){
    float c;
    switch(op){
       case '+': c=a+b; break;
       case '-': c=a-b; break;
       case '*': c=1.0*a*b; break;
       case '/': c=(1.0*a)/b; break;
    }
  return c;
}

float Getnumber (char *a){
    int n;         /* n digits*/
    int i; 
    int point;    /* float point location */
    float c; 

    n = strlen(a);

    if (a[0]=='.')
       return ;
    if (a[n-1]=='.')
       return ;
    point = n;

    for(i=1; i<n ; i++)
      if(a[i]=='.')
        point = i;

    c=0.0;     
    for(i=0; i< point; i++)
    c += (a[i]-48)* pow(10,(point-i-1));
    for(i=point+1 ; i< n; i++)
    c += (a[i]-48)* pow(10,(point-i));

    return c;
}

int In( char ch, char *OPS){

    int i;
    int flag=0;

    for (i=0;i< NUMOFOPR ;i++)
       if (ch==OPS[i]){
         return (TRUE);
         flag=1;
       }
    if (flag==0)
    return (FALSE);

}

char Compare( char x1,char x2 ){
     int i;
     int m,n;
     m=6;
     n=5;         /* to prevent array overflow */
     for(i=0;i<NUMOFOPR;i++){
       if(x1==OPS[i])
         m = i;
       if(x2==OPS[i])
         n = i;
     }
     return order[m][n];
}


int main(){
   seqstack1 operand;
   seqstack operator;
   char ch[Max];
   char *num;        /*  dynamic storage allocation */
   char x,op;
   int n,i,m;
   int first,last;
   float a,b,c,v;
   Initstack1(&operand);
   Initstack(&operator);
   Push(&operator,'#');
   printf("\n\nPlease input an expression (Ending with #): ");
   scanf("%s",ch);
   n = strlen(ch);
   v=0.0;
   for (i=0; i<n ; i++){
      if(ch[i] !='#'|| Gettop(&operator)!='#'){
         if(! In(ch[i],OPS) ){
            first = i;        /* record the number of first digit number */
            last = first ;    /* record the number of last digit number */
            while( !In(ch[last+1],OPS) )
               last++;
            num = (char *)malloc(sizeof(char)*(last-first+1));
            for(m=0,i=first;i<last+1;m++,i++)
               num[m]=ch[i];
            a = Getnumber(num);      /*用ch逐个扫面各位数码，并转换为十进制数a*/
            Push1(&operand,a);
            free(num); 
            i=last;

         }/* if */
         
         else
              switch (Compare(Gettop(&operator),ch[i])){
                  case '<': Push(&operator,ch[i]);
                            break;
                  case '=': Pop(&operator,&x);
                            break;
                  case '>': Pop(&operator,&op);
                            Pop1(&operand,&b);
                            Pop1(&operand,&c);
                            v= Execute(c,op,b);      /*对a和b进行op运算*/
                            Push1(&operand,v);
                            printf("%f\n",v);
                            i--;
                            break;
                  default:
                            printf(" Wrong operator !\n");
                            break;
              }/* switch */

      }/*if*/
      else
           break;
   }/* for */
  v = Gettop1(&operand);
  printf("%f,%d\n",v,n);
}