Intro to the Syntax

1
Intro to the Syntax
2
Using Visual C

• Create the Project .dsp a text file
  containing the names and locations of all files
  used for the program.
• Create the Workspace the environment where all
  of the files in your project are held a folder
  containing one or more projects and .dsw file.
• Create the Source File the file that contains
  the C code for your program (add to project) .

3
Comments

• Two Styles
• // - the remainder of the line will be ignored by
  the compiler
• / / - all of the text between the / and /
  will be ignored by the compiler (may be more
  than a single line)

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Preprocessor Directive

• includeltiostreamgt - we will use this at the
  beginning of every source file that we create in
  which we would like to use the cin and cout
  objects to read input from the keyboard and
  output to the screen

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The main Function

• int main()
• return 0
• main the name of the function equivalent to
  CONTROL in C
• int the return type of the main function
• () the (empty) parameter list for the main
  function
• return 0 the main function returns a 0 to
  signify successful program completion

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The cout Object and Stream Insertion Operator

• Stream Insertion Operator ltlt used to insert
  data into the output stream
• cout object in the iostream header file used to
  output data to the screen
• Example cout ltlt Hello
• Place the following preprocessor directive in all
  programs which use the cout object.
• includeltiostreamgt

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The cout Object and Stream Insertion Operator

• Place the following line in all programs which
  use the cout object.
• using stdcout
• You can use the following statement to include
  all members of the std namespace... however this
  will also include things that you dont need!
• using namespace std

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Escape Sequences

• \n Go to the next line
• \r Return to the beginning of the current
  line
• \t Tab to the next default tab stop
• \a Ring the system bell
• \ Used to output a
• \\ - Used to output a \

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The endl stream manipulator

• like \n, but different
• not an escape sequence dont put in quotes
• flushes the output stream output will be
  generated immediately
• The endl stream manipulator is also a member of
  the std namespace , so place
• using stdendl in programs that use it

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Variable Data Types

• int integers (positive and negative whole
  numbers)
• float real numbers
• double real numbers, more space than float
• char any ASCII character
• bool logical, true or false

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Declaring a Variable

• DataType variablename
• This sets aside a memory location to hold the
  variable
• The variable name must be a valid identifier
• No value will be placed in the variable

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Valid Identifiers

• identifier name for a variable, function or
  constant. May be any combination of alphanumeric
  characters and the underscore that does NOT begin
  with a numeral and is not a C keyword.
• Note C is CASE SENSITIVE!
• Valid identifiers Joe, x, august1st,
  _underscore,OneMore
• Invalid identifiers 4thOfJuly, c, int,
  one more

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Initializing Variables

• initialize giving a value before use.
  Example x 3
• assignment operator () commutes from right to
  left. The value on the LHS will be changed.
• cascading assignment operators commutes from
  right to left
• initializing and declaring in one statement
• Example int x 3

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Arithmetic Operations

• , /, , ,
• Order of Operations
• Operations are type dependent
• 1 / 4 - 0
• 1 / 4.0 - 0.25
• 1.0 / 4 - 0.25
• Note You can put an arithmetic operation in a
  cout statement. For example, cout ltlt x/2
  will print the value of x/2.

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Assignment Statements

• Commute right to left
• Example x y z 4
• Order of Operations must be followed

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The cin Object and the Stream Extraction Operator

• stream extraction operator - gtgt used to obtain
  data from the input stream
• cin - object in the iostream header file. Used to
  obtain input from the keyboard. The value of the
  variable on the RHS will be replaced
• Example cin gtgt x
• The cin object is also a member of the std
  namespace, so place using stdcin in files that
  use this object.

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If statements

• IF selection structure
• if ( logical expression )
• True Action(s)
• Ex if ( logical expression )
• cout ltlt True ltlt endl
• Braces are unnecessary if only one action
  occurs on the true side of the decision.

if (logical expression)
Print True
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Relational operators

• lt, lt, gt, gt, , !
• Each relational operator returns a logical value
• Example
• if ( x gt 10 )
• cout ltlt x is big ltlt endl

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Terminology

• Syntax Error error in usage of the language
  (like a grammatical error). Our compiler will
  catch our syntax errors.
• Logic Error syntactically correct code that
  does not perform the desired task.
• Run-time Error a mathematical error in your code

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Additional Notes on Writing C Programs

• Portability Tip Dont pass column 80 in your
  source code
• When turning in your program attach the source
  code (.cpp file) to an email