Variables A variable is something that may change in value. A variable might be the number of words on different pages of this booklet, the air temperature each day, or the exam marks given to a class of school children. A variable could be likened to a storage box whose contents may often change. The box, or variable must be given a name to distinguish it from others.
Commented lines are non executable so they can appear anywhere in the program.
The lack of specification often leads to program errors and it is strongly recommended that variable types are always declared. Numerical data may be separated into integer and real numbers. Real numbers cannot be stored accurately. The accuracy of a real variable depends on the computer. Constants Constants are quantities whose values do not change during program execution.