求输入数据绝对值 （C语言描述,EOF文件流）

解题思路:

            用while循环判断用户输入,if判断输入是正负数,如果是正数则保留两位小数原样输出,如果是负数就输出负数的相反值并保留两位小数

注意事项:

                注意while循环只允许一种循环条件

参考代码:#include<stdio.h>
                int main(void)
                {
                        float a;
                        while((scanf("%f",&a))!=EOF)                    //直到结束
                         {
                          if(a>0)                                                     //为正数时   
                                   printf("%.2f\n",a);                
                          else                                                        //不为正数时
                                   printf("%.2f\n",-a);                    
                         }
                         return 0;
                 }