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\begin_layout Standard
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Terminology for C programming
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\begin_layout Standard
Paul Johnson Feb.
 8, 2007
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\begin_layout Description
GNU An organization that creates and advocates for 
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free software
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\begin_layout Description
gcc The GNU C Compiler, AKA GNU Compiler Collection.
 A 
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compiler
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 is a program that makes programs.
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\begin_deeper
\begin_layout Quote
Example: 
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gcc -o whatever MyFile.c
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 will create an executable 
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./whatever
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 from a file MyFile.c
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\begin_layout Standard
Sometimes gcc commands become very complicated because it allows may options.
 See the output from 
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gcc --help
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\begin_layout Description
why\InsetSpace ~
the\InsetSpace ~
./ The current working directory is not, by default, in the 
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PATH
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.
 The dot-slash symbol means 
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look for an executable in the current working directory
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\begin_layout Description
binary A nontext file.
 You can't edit these with a 
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flat text
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 editor like Emacs, and generally doing so would destroy them.
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\begin_layout Description
object\InsetSpace ~
file\InsetSpace ~
(*.o) When gcc runs, it converts each file that contains C code
 into an object file, a binary thing in 
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machine code.
 After that, the 
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linking
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 process ties those 
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o
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 files together into an executable.
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\begin_layout Description
make A program that reads a 
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Makefile
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 and tells gcc how to compile a program, i.e., what options are required.
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\begin_layout Description
library A pre-existing 
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thing
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 containing routines and variables that programs can use.
 
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\begin_layout Description
so\InsetSpace ~
file\InsetSpace ~
(*.so) A 
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shared object
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 file.
 In Linux/Unix, library components are generally built into 
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so
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 files.
 The compiler can 
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link in
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 these objects with your program.
 An 
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so
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 file is generally accessed at 
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run time
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.
 In other words, the contents of the 
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so
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 file are not gobbled into your program when you compile it.
 In MS Windows, the equivalent is a DLL file (dynamic link library).
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\begin_layout Description
a\InsetSpace ~
file\InsetSpace ~
(*.a) A library that cannot be loaded at runtime.
 The compiler has to translate the contents of this library into your program
 
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statically
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.
 A statically linked program is bigger, but may run faster.
 Originally, all C programs were 
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statically linked
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 in this way, and the drain on system resources prompted the push for the
 use of shared object libraries.
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\begin_layout Description
header\InsetSpace ~
file\InsetSpace ~
(*.h) A file that lists the variables and functions available from
 a library.
 Almost always, the available header files are found in the filesystem under
 /usr/include.
 A program must declare that it intends to use elements from a library by
 including a reference to the header file.
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