Topic4 Introductory Computer Programming Language C

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Topic4 Introductory Computer Programming Language
C

• Introduction
• A Simple Input and Output Program
• Running a C Program
• Control Flow and Data Structures
• A Program Composed of Several Functions
• Running Single File Programs

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Programming Languages

• Low level programming languages
• Machine language
• Assembly language
• High level programming languages
• Basic, Fortran, Cobol, PL/1, Pascal
• C, C,Java
• Macro Languages Nuc Med Appl.

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C Language Functions

• Main reserved for main program
• int by default. Others must be defined. Void
  procedures
• Subprogram gt functions
• Variable name up and lower case.
• Data types int, float, double, char.
• Qualifiers int, long, short, unsigned

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Statements

• Assignment Statements
• variableexpression
• All Statements in C Return a Value
• a3 /assign a the value 3 /
• ba3 /assign b the value of a3 which is 3/
• printf (d \n, b4)
• / assign b the value 4 and print the result of
  the assignment which is 4 /

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Operators

• Operators , /, , -
• Increment , decrement --
• I increment I and then use its value in the
  expression, I use the value I and then
  increment it.
• Example
• int I,j,k
• I3j10
• jI / j is now 4, I is now 4 /
• j1 I7 j(I)-5 / j is now 2, I is now 8 /
• k--Ij /k is now 7214, I is 7, j is 3 /

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Assignment Operators

• Assignment Operators
• Variablevariable OP expression gt Variable OP
  expression Example x3 gt x x3
• Data Initialisation
• int I2 j6
• float x1.2
• char cs
• Blocks
• A group of statements as a single entity does
  not need a semi-colon value of the block last
  statement executed.

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Control Flow

• Control Flow
• selection if-then-else.
• Loops while, for.
• Switch multiway
• Selection
• if (integer - expression) block1 else block2
• While Loops
• while (integer - expression) while block
• Do-While Loops
• do do-while-block while (integer expression)

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For Loops

• For (expression1 expression2expression3)
• For block
• expression1 is evaluated before the loop is
  entered.
• expression2 is the loop control loop continues
  if it is true.
• Expression3 is executed at the end of each
  iteration.

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Variables

• Global variable
• scope a global variable declared in the same
  file
• not in a file external
• external variable
• use external if the global is defined below the
  function
• static variable
• keep a variable when function is returned.
• Static for global variable keep the variable
  local to the file.

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Pointer

• Pointer
• a variable that contains the address of other
  variable
• ampersand operator to access the address of a
  variable.
• Pointer arithmetic operation
• increment or decrement by the size of the item it
  points to. I.e. 4 integer

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Array

• Array
• name of the array is a pointer to the base
  address of the array.
• Square bracket.
• Array Initialisation
• int a56,9,5,20,30

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Character String

• Character String array of character. Null
  character as a terminator
• Multi-dimensional arrays
• int a510 / 5 rows, 10 columns /
• int I
• Ia34 /Example of normal array indexing /

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The C Preprocessor

• Before C Program Compilation
• include, define
• stdio.h
• example
• define ARRAY_SIZE 10 / change size here /
• int aARRAY_SIZE

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Input and Output

• printf (format-string, arg1, arg2, )
• format d
• special characters \n, \t.
• scanf

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User Defined Types

• Enumerated Type
• enum name enumerator1, enumerator2,
• include ltstdio.hgt
• enum colour red, orange, yellow, green, blue,
  violet
• main()
• enum colour my_suit_colour
• my_suit_colourorange / no taste, but legal /
• printf(my suit colour is d \n,
  my_suit_colour)

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Structures

• Treat a set of variables of different types as a
  single entity.
• Struct type_name
• type var_name1, var_name2,
• type var_name3, var_name4,
• Accessing Structures
• current_time.hour
• operator -gt

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Union

• Referencing the same storage location in
  different ways
• Union name
• type var1, var2,
• type var3, var4,

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Command Line Arguments

• Argc number of arguments
• argv values of arguments

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