应该这样写哦
#include<stdio.h> int main() { float x,y; printf("请输入提示信息"); scanf("%f",&x); if(x>1) printf("y=%f\n",2.5*x); else if(x>=-1&&x<=1) printf("y=%f\n",x); else printf("y=%f\n",3*x); return 0; }