Posted on 2008-10-30 08:48
dengbo 阅读(471)
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#include "stdafx.h"
#include"c1.h"
#include"c3-1.h"
#include "bo3-1.h"
#include<iostream>
#include<stack>
#include<vector>
#include<string>
using namespace std;
/**//*******定义优先级**********/
/**//**
+ - * / ( ) (进栈符号)
(栈顶符号)
+ > > < < < >
- > > < < < >
* > > > > < >
/ > > > > < >
( < < < < < <
) > > > > > >
***************************/
/**//******* > < 表示栈顶符号和要进栈符号的优先关系，
如果 栈顶符号的优先级>要进栈符号的优先级，执行计算；
如果 栈顶符号的优先级<要进栈符号的优先级，符号进栈***/
/**//*******返回栈顶符号是否优先与进栈符号*******/
char end[]="#";
bool is_prior_exe(char top, char in)
{
if(top == ')')
{
return true;
}
if(top =='(')
return false;
if(top == '*' || top=='/')
{
if(in!='(')
return true;
else
{
return false;
}
}
if(top=='+' || top=='-')
{
if( in=='+' || in=='-' || in==')')
{
return true;
}
if(in=='*' || in=='/' || in=='(')
{
return false;
}
}
}
bool In(char* c)
{
switch(c[0])
{
case'+':
case'-':
case'*':
case'/':
case'(':
case')':
case'#':return true;
default:return false;
}
}
vector<char *> get_word(string str)
{
vector<char *> word;
int i=0;
while(i<str.size())
{
if(str[i]=='('||str[i]==')'||str[i]=='*'||str[i]=='/'||str[i]=='+'||str[i]=='-')
{
char *temp = new char[2];
temp[0]=str[i];
temp[1]=='\0';
word.push_back(temp);
}
if((str[i]-'0'>=0 && str[i]-'0'<=9)||str[i]=='.')
{
static int j=-1;
static char *tmp;
if(j==-1)
{
j=i;
tmp=new char[15];
}
tmp[i-j]=str[i];
if(i+1<str.size() && (str[i+1]-'0'<0 || str[i+1]-'0'>9)&&str[i+1]!='.')
{
tmp[i+1-j]='\0';
word.push_back(tmp);
j=-1;
}
else if(i+1==str.size())
{
tmp[i+1-j]='\0';
word.push_back(tmp);
j=-1;
}
}
i++;
}
word.push_back(end);
return word;
}
double ConvertStrToDouble(char * exp)
{
//get integer
int num1=0;
while(*exp!='\0'&& *exp!='.')
{
num1=num1*10+ (*exp-'0');
exp++;
}
if(*exp=='\0')
{
return num1;
}
//get decimal
double num2=0;
while(*exp!='\0')
{
*exp++;
}
*exp--;
while(*exp!='.')
{
num2=num2*0.1+(*exp-'0');
*exp--;
}
num2=num2*0.1;
return num1+num2;
}
double Operate(double a,char theta, double b)
{
//int c;
//a=a-48;
//b=b-48;
double c;
switch(theta)
{
case'+':c=a+b;
break;
case'-':c=a-b;
break;
case'*':c=a*b;
break;
case'/':c=a/b;
}
return c;
}
char Precede(char t1, char t2)
{
char f;
switch(t2)
{
case'+':
case'-':if(t1=='(' || t1=='#')
f='<';
else
f='>';
break;
case'*':
case'/':if(t1=='*' || t1=='/' || t1==')')
f='>';
else
f='<';
break;
case'(':if(t1==')')
{
printf("ERROR\n");
exit(0);
}
else
f='<';
break;
case')':switch(t1)
{
case'(':f='=';
break;
case '#':printf("ERROR2\n");
exit(0);
default:f='>';
}
break;
case'#':switch(t1)
{
case'#':f='=';
break;
case'(':printf("ERROR3\n");
exit(0);
default:f='>';
}
}
return f;
}
double EvaluateExpression(vector<char*> cpvec)
{
stack<char> OPTR;
stack<double> OPND;
//SElemType a,b,c,x,theta;
//InitStack(&OPTR);
//Push(&OPTR,'#');
double num_first,num_second;
char theta;
OPTR.push ('#');
//InitStack(&OPND);
//c=getchar();
//GetTop(OPTR,&x);
char c_top = OPTR.top();
int i=0;
while(i<cpvec.size())
{
if(In(cpvec[i]))
{
char c_in = cpvec[i][0];
bool flg =false;
do
{
switch(Precede(c_top,c_in))
{
case'<':OPTR.push(c_in) ;/**//*Stack top Prior lower Push Stack*/
c_top = OPTR.top();
flg=false;
break;
case'=':OPTR.pop();/**//*off bracketd Pop Stack*/
if(!(OPTR.empty()))
c_top = OPTR.top();
flg=false;
break;
case'>':theta=OPTR.top();
OPTR.pop(); /**//*Stack top Prior higher Pop Stack calculate*/
c_top=OPTR.top();
num_first=OPND.top();
OPND.pop();
num_second=OPND.top();
OPND.pop();
OPND.push (Operate(num_second,theta,num_first));
flg=true;
break;
}
}
while(flg);
}
else if(cpvec[i][0] >='0' && cpvec[i][0]<='9')/**//*c is number*/
{
double tmp = ConvertStrToDouble(cpvec[i]);
OPND.push(tmp);
}
else /**//*c is illegal character*/
{
printf("ERROR$\n");
exit(0);
}
//GetTop(OPTR,&x);
i++;
}
return OPND.top();
}
int _tmain(int argc, _TCHAR* argv[])
{
//printf("Input a arithmetic expression use '#' to end");
char ch;
while((ch=getchar())!=EOF)
{
cout<<"Input a arithmetic expression"<<endl;
string expstr;
cin>>expstr;
vector<char *>cpvec =get_word(expstr);
cout<<"result="<<EvaluateExpression(cpvec)<<endl;
}
system("pause");
return 0;
}