programming-for-dummies

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Organizing a Program
More versus fewer keywords
Computer scientists are divided on whether it’s
better for a programming language to offer a lot
of keywords:
By offering a lot of keywords, a programming
language can let programmers write
fewer keywords that do more work.
By offering fewer keywords, a programming
language makes programmers write
a lot of simple keywords just to do something
that another language might be able
to do with one keyword.
Given these choices, having a lot of keywords
in a programming language seems to make
more sense. The problem is that the more keywords
used, the harder it is to write a compiler
for that programming language. The harder it is
to write a compiler, the less efficient that compiler
is in converting source code into machine
language, just as it’s much harder to translate a
Russian scientific paper into English than it is to
translate a Russian children’s story into English.
That’s one problem with the Ada programming
language. Ada uses lots of keywords, which
makes programming easier but creating compilers
for Ada much harder. This is one of the
reasons why Ada compilers are much less
widespread than compilers for the C programming
language.
Unlike Ada, C offers a bare minimum of keywords.
This makes programming in C harder
because you need to write a lot of keywords to
do something as seemingly simple as storing a
text string. However, C’s handful of keywords
makes it much easier to write a C compiler.
To compensate for the lack of keywords, most
C compilers include libraries of commonly used
subprograms that can make C programming
easier and more useful.
As a result, you can find C compilers for practically
every computer because it’s much easier
to write a C compiler than it is to write an Ada
compiler. The more C compilers available, the
easier it is to transfer (port) a C program to
another computer. The C programming language
is popular partly because you can run C
programs on almost every computer.
With a lot of keywords, Ada makes programming
easier for humans but harder for computers.
In contrast, a handful of keywords in C
makes programming harder for humans but
much easier for computers. Given a choice
between Ada or C, more people choose C, so
having a programming language with fewer
keywords seems to be more efficient (at least
for the computer).
Organizing a Program
Every program consists of one or more commands, but there are different
types of commands. Some commands tell the computer how to manipulate
data, such as adding two numbers together. Other commands might tell the
computer how to print data, display it on-screen, or save it on a disk.
Although you could jumble all your commands together and still have a
working program (see Book 1, Chapter 2 for more on programs), make your
program easier to read and modify by organizing similar commands in different
parts of your program.