Imagine a program with 1000 lines. (This may seem large to you, but
it is actually quite small.) It is much easier to write a properly
designed program consisting of 20 50-line functions than it is to
write a program consisting of one 1000-line main program. Functions
can be written and understood independently of one another. It is
much easier to get your mind around a 50-line thing than a 1000-line
Another benefit is that code can be reused between projects. If
someone has previously written a function that you would like to use,
it is a simple matter to incorporate it into your program.
A third benefit is that the use of functions can eliminate the
duplication of code. If the duplicated code is long enough, the use
of functions can actually shorten a program.
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