Let's take a quick review of all that we have learned about programming
languages in these lessons.
- We began by introducing the three
generations of programming languages: machine code, assembly languages,
and high-level programming languages.
- We examined how variables and constants are named using identifiers.
Identifiers are descriptive names that are mapped to locations in the
computer's memory. Once a memory location is given a specific name,
we can refer to that location using the identifier rather than the numeric
- We saw how the contents of a variable could be changed with assignment
statements and expressions.
Expressions are mathematical combinations of numbers, variables, and
constants. Boolean expressions
are expressions that represent values which are either true or false.
- We found that some expressions do not make sense because the variables
are not compatible. Thus, our variables need a specific type to identify
what variables are compatible and what operations can be performed on
those variables. Some of the data
types we saw were integer, real, character, Boolean, and an aggregate
type called an array.
- We learned that the flow
of control in a program proceeds sequentially from one statement
to the next. This flow of control can be altered using three constructs:
- We saw that programming languages support two types of input
and output: interactive user I/O and non-interactive file I/O.
- We examined a complete
program to see how the individual parts of a program such as I/O,
procedures, functions, and control logic fit together to make this finished