#include<stdio.h>
void print(void);
float getnum(void);
char getletter(void);
char getletter1(void);
int main(void)
{
   float number1,number2;
   char choice;
   print();
   while ((choice = getletter1() )!= 'q')
   {
       printf("enter first number:\n");
       number1 = getnum();
       printf("enter second number:\n");
       number2 = getnum();
       switch (choice)
       {
       case 'a':printf("%g+%g=%g\n", number1, number2, number1 + number2); break;
       case 's':printf("%f-%f=%f\n", number1, number2, number1 - number2); break;
       case 'm':printf("%f*%f=%f\n", number1, number2, number1*number2); break;
       case 'd':if(!number2)
       printf("enter a number other than 0;\n"); number2 = getnum();
       printf("%f/%f=%f\n", number1, number2, number1 / number2); break;
       }
       printf("\n");
       printf("\n");
       printf("\n");
       print();
   }
   printf("bye!\n");
   return 0;
}
void print(void)
{
   printf("enter the operation of your choice:\n");
   printf("a.add s.subtract\n");
   printf("m.multiply d.divide\n");
   printf("q.quit\n");
}
float getnum(void)
{
   float number;
   char ch;
   while (scanf("%g", &number) != 1)
   {
       while ((ch=getchar() )!= '\n')
       {
           putchar(ch);
           printf(" is not a number.\n");
           printf("please enter a number,such as 2.5,-1.78e8 or 3:\n");
       }
       while (getchar() != '\n')
           continue;
   }
   return number;
}
char getletter(void)
{
   int ch;
   ch = getchar();
   while (getchar() != '\n')
       continue;
   return ch;
}
char getletter1(void)
{
   int ch;
   ch = getletter();
   while(ch!='a'&&ch!='s'&&ch!='m'&&ch!='d'&&ch!='q')
   {
       printf("please respond with a,s,m,d.\n");
       ch = getletter();
   }
   return ch;
}

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关于给cfree5配置c++11特性后的问题

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