gistfile1.c

#include <stdio.h>
int main()
{
	float a,b;
	char c1;
	printf("请输入表达式\n");
	scanf("%f%c%f",&a,&c1,&b);
	printf("运算结果为:");
	switch(c1)

  {
    case '+': printf("%f+%f=%f\n",a,b,a+b);break;
    case '-': printf("%f-%f=%f\n",a,b,a-b);break;
    case '*': printf("%f*%f=%f\n",a,b,a*b);break;
    case '/': if (b!=0.0)

		      printf("%f/%f=%f",a,b,a/b);

		     else
			
			printf("运算错误!除数不可以是0!\n");break;

	    default : printf("运算错误!除数不可以是0!\n");

  }

}