main( )
{float x,y;
int i;
scanf("%f",&x);
if(x<0) y=x+5;
else if( x<=5) y=2*x+1;
else y=x ;
printf("x=%.2f,y=%.2f\n", x,y);
}
https://blog.csdn.net/weixin_30287169/article/details/95738502