C++ Class 2: A Simple Program

A Simple Program:

Printing a Line of Text

• Comments
• Document Programs
• Improve program readability
• Ignored by compiler
• Single-line comment
• Begin with //
• Multiple-line comment
• Everything between /* and */ is ignored
• Preprocessor directives
• Processed by preprocessor before compiling
• Begin with #
• #include
• #define

C++ Preprocessor

• C++ Compilers automatically invoke a preprocessor that takes care of #include statements and some other special directives.
• You don't need to do anything special to run the preprocessor - it happens automatically.

The Preprocessor

• Lines that start with the character '#' are special instructions to a preprocessor.
• The preprocessor can replace the line with something else:
• include: replaced with contents of a file
• Other directives tell the preprocessor to look for patterns in the program and do some fancy processing.

Preprocessing

1. C++ Program
2. C++ Preprocessor
3. Temporary file (C++ program)
4. C++ Compiler
5. Executable Program

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Output of above program:

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The program was written in Microsoft Visual C++ 6.0

You can use any compiler which you find easy to use but I suggest you to use Microsoft Visual C++  6.0 or Borland in the beginning if you want to be a good programmer.

• Output stream object
• cout
• "Connected" to screen
• <<
• Stream insertion operator
• Value to right (right operand) inserted into output stream
• Namespace
• using namespace std; specifies that we are using objects from "namespace" std
• Escape character and escape sequences
• \ is called the "Escape Character"
• Indicates "special" character output

Some Escape Characters:

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(To be continued)