One Dimensional Arrays

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Chapter 12

• One Dimensional Arrays

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C Data Types

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Structured Data Types

• Struct
• Class
• Union
• array

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Structured Data Typearray

• Array linearly-ordered collection of
  homogeneous data elements (collection of elements
  of the same type)
• Linearly-ordered there is a first, second,
  third, etc. element

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Array Properties

• All elements in the array are of the same type.
• Elements are accessed by their index, starting at
  0
• Size of the array is fixed (cannot be increased
  or decreased once an array has been created)

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Why use arrays?

• Gives use the ability to store a large number of
  elements using one variable name.
• Examples
• Suppose we want to store 3 test grades int t1,
  t2, t3
• How could we store 100 test grades?

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Using C array

• Declare the array
• Initialize the array
• Access the array
• Passing an array as an argument

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How to declare an array

• Examples
• int numbers10//stores 10 integers
• float averages30 //stores 30 floats
• --------------------------------------------
• //Better to use const
• const int CLASS_SIZE 25
• string namesCLASS_SIZE

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You may want to initialize an array

• You can use a loop
• int numbers10
• for (int i0 ilt10 i)
• numbersi0
• 2) string names5 Sam, Joe, Carol,
  Bill, Jane

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How to Access array elements

• Must use an index (subscript)
• Index starts with 0
• Examples
• cout ltlt numbers4 ltlt endl
• //prints the 5th element in the array

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How to access array elements (continued)

• int grades10
• cout ltltEnter 10 test grades\n
• for (int i0 ilt10 i)
• cin gtgtgradesi

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Array Assignments

• Examples
• grades5 89
• grades5 grades4
• --------------------------------------------
• int a3
• int b3
• ab //illegal

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Questions!

• Assume that we have an array of integers called
  numbers of size, SIZE.
• Show code to declare the array
• int numbersSIZE
• Show code to initialize the array to 0s.
• for (int i0 iltSIZE i)
• numbersi0

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QUESTIONS

• 3) Show code to print all the numbers in the
  array
• for (int i0 iltSIZE i)
• cout ltltnumbersi ltlt endl
• 4) Show code to print the 5th number in the array
• cout ltltnumber4 ltlt endl

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QUESTIONS

• How many memory cells are reserved for data and
  what type of data can be stored there?

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BE CAREFULL!

• C does not check for out-of-bounds array
  indexes. For example, suppose
• float alpha100
• The valid range of alpha is 0 through 99.
• Assume
• alphai62.4
• This is out-of-bounds if i is less than 0 or i is
  greater than 99!

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Passing an array as a parameter

• Assume
• const int TOTAL 10
• float finalGrade
• int gradesTOTAL
• Function prototype
• float average(int , int)
• Function call
• finalGrade average(grades, TOTAL)
• Function heading
• float average (int numbers, int size)

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Array Notes

• Arrays are always passed by reference!
• The address of the beginning of the array is
  passed as an argument to the function

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HomeworkQuiz Grade

• Write a function called Smallest() which
  receives as arguments an integer array called A
  and an integer called Count where A has been
  given values and Count is the total number of
  integers found in the array. The function should
  return the smallest integer found in the array.