invalid type argument of `unary *'

[nsbcnjsbc]

What's wrong?here's the code

#include<stdio.h>
#include<stdlib.h>
#define pi  3.141592;
 
int main(void)
{
 
float radium,diameter,perimeter,area;
 printf("please input radium：");
 scanf("%f",&radium);
 diameter =2.0*radium;
 perimeter =2.0*radium*pi;
 area=radium*pi*radium;
 printf("the diameter：%f\n the perimeter：%f\nthe area%f\n",diameter,perimeter,area);
 
 
 
  system("PAUSE");    
  return 0;
}

[Banfa]

The problem is not with the * operator, it can be chained as it is at line 13 if all the operands are variables or constants.

The problem all the operands are not variables or constants because at line 3 you have put a semi-colon at the end of your definition of pi which means that after preprocessing line 13 looks like this

area=radium*3.141592;*radium;
 

With the extra ; the second * forms part of a second expression and it only has 1 operand so it is treated as the unary dereference operator, this operator operates on pointers and radium is a float so you get the error

[i]error: invalid type argument of unary '*' (have 'float')/I]

Remove the ; from line 3