It is red. The color is blue. The color is red. The Pascal program, ifdef.p, which first checks if bird1 has been defined. If bird1 has been defined, the program checks whether or not it needs to define bird2.
Conditional variables are false by default.
The Pascal program, enable.p. Two is defined as -32768. So you can put anything here. If no such directive exists, pc proceeds to the next statement. The expression consists of a conditional variable and the optional boolean operators and, or, and not.