表达式求值

#include<stdio.h>   
#include<string.h>   
#include<stdlib.h>   
char str[1005];  
int start;  
char s[50],ss[50];int i,j;  
double Term();double Expression();double Factor();  
double Term()  
{  
    double f=Factor(),t;  
    --start;  
    if(str[start]=='*')  
    {  
        t=Term();  
        return t*f;  
    }  
    else if(str[start]=='/')  
    {  
        t=Term();  
        return t/f;  
    }  
    else {++start;return f;}  
}  
double Expression()  
{  
    double t=Term(),e;  
    --start;  
    if(str[start]=='+')  
    {  
        e=Expression();  
        return e+t;  
    }  
    else if(str[start]=='-')  
    {  
        e=Expression();  
        return e-t;  
    }  
    else {++start;return t;}  
}  
double Factor()  
{  
    --start;  
    double ret;  
    if(str[start]==')')  
    {  
        ret=Expression();  
        --start;  
        return ret;  
    }  
    else  
    {  
        i=0;  
        memset(ss,0,sizeof(ss));  
        while((str[start]>='0'&&str[start]<='9')||str[start]=='.')  
            s[i++]=str[start--];  
        ++start;  
        for(j=0;j<i;j++)  
        {  
            ss[j]=s[i-1-j];  
        }  
        return atof(ss);  
    }  
}  
int main()  
{  
    //freopen("1.txt","r",stdin);   
    int n;  
    scanf("%d",&n);  
    while(n--)  
    {  
        scanf("%s",str);  
        start=strlen(str)-1;  
        printf("%.2lf\n",Expression());  
    }  
}