Multi c File

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Multi-file C++ ProgramsCS1044

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Single File C Programs

So far all of the programs we have looked at in this

class have lived in a single file

As your programs become more complex it can becumbersome to put all of the code into a single file

Eventually youll want to, or need to, put your C++

code in multiple filesIdeally, this makes logically breaks down your code

further, making it easier understand



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Single C++ File Example

#include // includes

doubleaverage(inta, intb); // prototypes

// mainintmain(){ cout


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Multiple C++ Files

But lets say you wanted to implement your own vector

type or some other domain specific data structure

Ideally youd write it once and then use it over and over

again, not rewrite it every time

So embedding complex and generic data types into

your main.cpp file is not ideal, or even structures like inProject 3

Another example: a program with 10,000 lines in a

single file, can be broken down by functionality



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Multiple C++ Files

For more interesting C++ programs, the code is

typically organized into a collection of header files and

cpp files

Header files end in .hi.e. myfile.hand cpp files

look like just main.cpp

In most cases, the header filescontain only typedeclarations and function prototypes, while the cpp

filescontain the corresponding implementations.



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Multiple C++ Files

Youve been #include

ing since almost day

one

When writing large C++ fortunately, you can also#includeyour own files

Like we mentioned earlier .h files contain declarations

Let say we are writing our own vector type and wevestored in myvector.cppand myvector.h

In main:#include myvector.h, notice the rather

than



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Typical C++ Program

Organization



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Multiple Inclusion Problem

#includedirectives are used within both .hand .cpp

files to import declarations as necessary.

However, there is potential danger:

As written we will have multiple

copies of the stuff in B.h

This will cause errors



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However, there is a simple fix, by adding 3 lines to all

of your .h files



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These 3 lines are the the same in pretty much every .h

file except the bold part is different:

The convention is to just capitalize the file name and

replace the . with _Wednesday, April 24, 13


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A Final Example

Wednesday April 24 13

Documents

Multi c File