True False

/**
 * True/False. 
 * 
 * A Boolean variable has only two possible values: true or false. 
 * It is common to use Booleans with control statements to 
 * determine the flow of a program. In this example, when the
 * boolean value "x" is true, vertical black lines are drawn and when
 * the boolean value "x" is false, horizontal gray lines are drawn. 
 */
 
bool b = false;

size(640, 360);
background(0);
stroke(255);

int d = 20;
int middle = width / 2;

for (int i = d; i <= width; i += d) {
  
    if (i < middle) {
        b = true;
    } else {
        b = false;
    }
  
    if (b == true) {
        // Vertical line
        line(i, d, i, height - d);
    }
  
    if (b == false) {
        // Horizontal line
        line(middle, i - middle + d, width - d, i - middle + d);
    }
}