C Syntax and Semantics and the Program Development Process

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C Syntax and Semantics and the Program
Development Process

• Jianhua Yang
• Department of Computer Science
• University of Houston

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Goals

• The structure of C program
• Syntax templates
• C identifiers
• Char and string
• Reserved words in C
• Assigning values to variables
• String expressions
• Output statement/format
• Comments
• Simple C programs

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2.1 The Elements of C Program

• 1. C program structure
• Composed of one or more functions plus
  declaration part
• One and only one main function

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2.1 The Elements of C Program

• Example

include ltiostreamgt using namespace std int
Square(int ) int Cube(int ) int main()
coutltltThe square of 27 isltltSquare(27)ltltendl
coutltlt and the cube of 27 isltltCube(27)ltltendl
return 0 int Squre ( int n) return nn
int Cube( int n ) return nnn
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2.1 The Elements of C Program

• 2. Syntax and Semantics
• Syntax Grammar
• Semantics Meaning

the formal rules governing how valid
instructions are written
The set of rules that determines the meaning of
instructions
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2.1 The Elements of C Program

• 3. Syntax templates
• A syntax template is a generic example of the C
  construct being defined.
• Example MainFunction, Identifier

int main() Statement
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2.1 The Elements of C Program

• 4. Identifiers
• A name associated with a function or data object
  and used to refer to that function or data object
• Are made up of letters, digits, and underscore
  character, but must begin with a letter or
  underscore

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2.1 The Elements of C Program

• Valid identifiers
• Invalid identifiers

sum_of_squares J9 box_22A GetData Bin4D
40Hours Get Data box-22 cost_in_ int
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2.1 The Elements of C Program

• 5. Data and Data types

Storage attribute
Standard type int float char User-defined
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2.1 The Elements of C Program

• char
• Built-in
• Consisting of one alphanumeric
• string
• Program-defined
• Is a sequence of characters

A, a, 8,,,
Problem Solving, C, ,
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2.1 The Elements of C Program

• 6. Declarations
• Variable
• Constant

A statement that associates an identifier with a
data object, a function, or a data type so that
the programmer can refer to that item by name
A location in memory, referenced by an
identifier, that contains a data value that can
be changed
Is a value that can not be changed, including
literal value, and named constant
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2.1 The Elements of C Program

• Variable
• int empNum
• char ch
• Constant
• A, _at_, Programming in C
• const string STARS
• const char BLANK

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2.1 The Elements of C Program

• 7. Executable statements

The statements that work (react) on running time
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2.1 The Elements of C Program

• Assignment statement
• Function
• Syntax template
• Example
• Some points

To store a value to a variable
VariableExpression
firstNameAbraham TitlePresident i5 X123
.12

• consistent type
• Left hand must be variable
• Right hand must be expression

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2.1 The Elements of C Program

• Expression
• An arrangement of identifiers, literals, and
  operators that can be evaluated to compute a
  value of a given type

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2.1 The Elements of C Program

• Invalid assignment statement

string firstName string lastName char
letter char middleInitial middleInitialA. l
etterfirstName EdisomlastName lastName
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2.1 The Elements of C Program

• String expression and operator

Operator Joining or concatenating
string bookTitle string phrase1 string
phrase2 phrase1Programming and phrase2Prob
lem Solving bookTitlephrase1 phrase2 in
C .
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2.1 The Elements of C Program

• 8. Output
• Syntax template
• examples

coutltltexpression
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char ch2 string fName, lName fNameMarie
lNameCurie coutltltch coutltltfName
lName coutltltfNameltltlName coutltltfNameltltendlltltlNam
e
Marie Cure
Marie Curie
MarieCurie
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2.1 The Elements of C Program

• 9. Comments
• /xxxxxxx/
• /xxxxx
• xxxxx
• xxxxx/
• //xxxxxxx

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2.2 Program Construction

• Brief review
• Identifiers
• Declarations
• Variables
• Constants
• Expressions
• Statements
• comments

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2.2 Program Construction

• 1. Program Construction
• Program
• Function
• Block
• Statement

Declaration FunctionDefination FunctionDefinatio
n
Heading Statement
Statement
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2.2 Program Construction

• 2. C preprocessor
• Include directive
• Syntax template
• Example

Physically insert the contents of the named file
into your source program
include ltfile_namegt
include ltiostreamgt include ltstringgt
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2.2 Program Construction

• 3. Namspaces
• Why do we use Namespaces?
• Two accessing ways
• Examples

Some programmer-defined identifiers are declared
in a namespace with a specific name
include ltiostreamgt using namespace std int
main() coutltltNamespace Testingltlt endl
return 0

• Direct way stdcout
• 2. Indirect way using namespace std

include ltiostreamgt int main()
stdcoutltltNamespace Testingltlt stdendl
return 0
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2.3 Reviewa real program

• //
• //This is a real program. It would help you to
  
• // understand what we have learned in this
  chapter.
• //
• include ltiostreamgt
• include ltstringgt
• using nmaespace std
• const string TITLEDr.
  // Salutary title
• const string F_NAMEMargaret //First
  name of addressee
• const string M_INITIALH
• const string L_NAMESklaznick

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2.3 Reviewa real program

• int main()
• string first // Holds the first name plus
  a blank
• string FullName //complete name,
  including title
• string firstLast
• string titleLast
• //Creat first name with blank
• first F_NAME
• // Create full name
• fullnameTITLE first M_INITIAL
• fullnamefullName.L_NAME
• coutltltfullNameltlt is a GRAND PRIZE
  WINNER!!!ltltendlltltendl