C++ 实现一个简单的计算器 类

#include <stdio.h>  
#include <math.h>  
#include <ctype.h>  
#include <stdlib.h>  
#include <string.h>  
#define PI (3.14159265358979323846/180.0) //改为角度输入  
#define EPS (1e-7)        //浮点数比较  
#define N 8               //函数名称字符的最大长度   
//#define M 7               //现支持函数个数  
#define MAX_INFIX 128     //表达式的最大长度   
  
double EvExpre(void);     //表达式求值函数   
  
int main( void )   
{   
    while(8)   
    {   
        printf("\n请输入计算表达式:");   
        rewind(stdin);   
        printf("表达式值为:%.13lg\r",EvExpre());   
    }   
    return 0;   
}   
static double ftoa_zw(char *c)       //字符转实数   
{   
    double  n=0.0;   
    if(isdigit(*c))   
        do  
        {   
            n=n*10.0+(*c-'0');   

        }   
        while(isdigit(*c=getchar()));   
    if(*c=='.')   
    {   
        double m=1.0;   
        while(isdigit(*c=getchar()))   
        {   
            n=n*10.0+(*c-'0');   
            m*=10.0;   
        }   
        n /= m;   
    }   
    return n;   
}   
static int isfunc(const char *cur)//是否是函数符(是返回下标，否返-1)   
{   
    const char *ap[]= {"sin","asin","cos","acos","tan","exp","log",NULL};   
    const char **i;   
    for(i=ap;*i!=NULL; ++i)   
        if(strcmp(*i,cur)==0)   
            return (int)(i-ap);   
    return -1;   
}   
static double mathfuc(double n,int i)//函数运算   
{   
    double (*f[])(double)= {sin,asin,cos,acos,tan,exp,log,NULL};//一一对应   
    if(i<0 || i>= sizeof(f)/sizeof(f[0])-1 )   
    {   
        puts("程序异常退出...");   
        exit(-1);