int main( void )

{

double x = 0.0, num = 3.0, denom = 1.0;

int loop, ac;

ac = 4;

for ( loop = 1; loop <= ac; loop++ ) {

if ( loop % 2 != 0 )

x += num / denom;

else

x -= num / denom;

denom += 2.0;

}

printf( %.2f ", x );

return 0;

}

please explain the code