How can one write a c program to compute the area of a circle

Answer 1

This seems like a homework question, so I won't recommend anyone giving the full code.

But this is too basic. You know about pi*r*r math formula, just apply it.

Answer 2

#define PI 3.14159265358979

int main(){
//take radius as input with scanf

//apply the formula

//printf output
return 0;
}
or const float PI = 3.14..