calculator

#include <stdio.h>
#include <stdlib.h>

typedef enum
{
    FALSE = 0,
    TRUE
}BOOL;

void calculator(void);

int main(void)
{
    char y = ' ';
    y = 'y';
    while('y' == y)
    {
        printf("start calculator:\n");
        calculator();
        printf("restart?,printf 'y' to continue\n");
        scanf("  %c",&y);
        printf("%c\n",y);
    }
    return 0;
}

void calculator(void)
{
    char c;
    char ucOperator = ' ';
    int  k = 1;
    int value = 0;
    int lastValue = 0;
    int result = 0;
    int lastk;

    printf("start calculator input:\n");
/*    while((c = getchar()) == '\n'||c == ' ')
    {
        ;
    }
//this does work,the below way is more simple
*/
    scanf(" %c",&c);    //filter space and return
    do{
        if(c >= '0' && c <= '9')
        {
            if(!value)
            {
                value = c - '0';
            }
            else
            {
                value = value*10 + c- '0';
            }
            continue;
        }


        if('+' == c)
        {
            lastk = k;
            k =  1;
        }
        else
        {
            if('-' == c)
            {
                lastk = k;
                k = -1;
                c = '+';
            }
        }

         switch(c)
         {
         case '+':
             switch(ucOperator)
             {
             case '*':
                 result +=  lastValue * value * lastk;
                 break;
             case '/':
                 result +=  lastValue / value * lastk;
                 break;
             case '+':
                 result += value * lastk;
                 break;
             case ' ':
                 result += value;
                 break;
             default:
                 break;
             }
              ucOperator = '+';
             break;

         case '*':
             lastValue = value;

              ucOperator = '*';
             break;
         case '/':
             lastValue = value;

              ucOperator = '/';
             break;
         case '=':
             if('+' == ucOperator)
             {
                 result += value * k;
             }
             if('*' == ucOperator)
             {
                 result += value * lastValue * k;
             }
             if('/' == ucOperator)
             {
                 result += lastValue / value * k;
             }
             printf("%d\n",result);
             result = 0;
             ucOperator = ' ';
             break;
         default:
             break;
         }
         value = 0;
    }while((c = getchar()) != '\n');
}