Why my code show error ?

Question

#include <stdio.h>
int area(int x);
int main() {
int x;
int a=area( x);
scanf("%d",&x);
printf ("the area of %d radius circle is :%d",x,a);
return 0; }

int area(int x) {
x=x++;
return (x);
}

Answer 1

Mr. Unknown
How can you use "x" before taking input 😁.
Just change the line: scanf <--> int a

Answer 2

Ohh! I put right formula 22/7*r*r but because of the code show error frequently l used some other equation to see where is the error ?And it copied and pasted here ....