#include <stdio.h>

float square( float x )                  
{
   float r;         // Define a local variable         

   r = x * x;       // Statement

   return ( r );    // Return statement
}

int main( int argc, char *argv[] )
{
   float a, b;

   a = 4.0;

   b = square( a );  // Call function square

   printf("a = %f, b = %f\n", a, b);
}