为什么会运行不了，有大神可以帮帮我吗?

#include<stdio.h>
int star();
 float area(float x);
float tiji(float x,float y);
int main()
{
 float x,y;
 scanf("%f%f",&x,&y);
 star();
 printf("正方形面积:%.0f\n",area(x));
 star();
 printf("体积面积:%.0f\n",tiji(x,y));
}

int star()
{

 printf("*************************\n");
 return 0;
}