Elements of a C Program

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Elements of a C Program

• Hello World

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The Hello World Program
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Starts comments
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Comments
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Preprocessor directive
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Include a file
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Include the file iostream.hneed iostream.h to be
able to use cout
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Find the file in the standard placeC\Program
Files\Microsoft Visual Studio\VC98\Include\
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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The main function
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Main function returns an integer
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Encloses the main function
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Used to print to the screen
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Insertion operator
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Contains a string
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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String to be printed to the screen
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Indicates newline
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Terminates a statement
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Exit the function
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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Value returned from function
// the Hello World program include
ltiostream.hgt int main() cout ltlt "Hello
World!\n" return 0
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A brief look at cout
// Listing 2.2 using cout include
ltiostream.hgt int main() cout ltlt "Hello
there.\n" cout ltlt "Here is 5 " ltlt 5 ltlt
"\n" cout ltlt "The manipulator endl writes a new
line to the screen." ltlt endl cout ltlt "Here is a
very big number\t" ltlt 70000 ltlt endl cout ltlt
"Here is the sum of 8 and 5\t" ltlt 85 ltlt
endl cout ltlt "Here's a fraction\t\t" ltlt
(float) 5/8 ltlt endl cout ltlt "And a very very
big number\t" ltlt (double) 7000 7000 ltlt
endl cout ltlt "Dont't forget to replace Jesse
Liberty with your name...\n" cout ltlt "Tom Ray
is a C programmer!\n" return 0
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Types of comments
include ltiostream.hgt int main() / this is a
comment and it extends until the
closing star-slash comment mark / cout ltlt
"Hello World!\n" // this comment ends at the
end of the line cout ltlt "That comment
ended!\n" // double slash comments can be alone
on a line / as can slash-star comments
/ return 0
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Functions
include ltiostream.hgt // dunction Demonstration
Function // prints out a useful message void
Demonstration Function() cout ltlt "In
Demonstration Function\n" // function main -
prints out a message, then // calls
DemonstrationFunction, then prints out // a
second message. int main() cout ltlt "In
main\n" DemonstrationFunction() cout ltlt "Back
in main\n" return 0