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ARRAYS CHAPTER#04

ARRAYS CHAPTER#04. BS COMPUTER SCIENCE UNIVERSITY OF SWAT. ARRAYS. Array is a sequence of objects of same data type. The objects in an array are also called elements of the array. Represented in the computer memory by a consecutive group of storage locations.

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ARRAYS CHAPTER#04

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  1. ARRAYSCHAPTER#04 BS COMPUTER SCIENCE UNIVERSITY OF SWAT

  2. ARRAYS • Array is a sequence of objects of same data type. • The objects in an array are also called elements of the array. • Represented in the computer memory by a consecutive group of storage locations. • Referenced by a single variable called array name.

  3. Each element is referenced by its position in the array. • The position of an element in an array an index value or subscript. • In an array with n elements, the index values are 0,1,2,…,n-1. • 0 represent the index value of first element and so on and n-1 represent the index value of last element.

  4. How elements of array is accessed? • An element of an array is accessed by its subscript value. The index or subscript value is written inside a pair of square brackets [ ] with the name of the array.

  5. For which purpose array is used? • Array is used to process a large amount of data of same data type. The data is stored in an array. • The array is accessed by a single variable name. The index values are used to access individual elements of the array. • As few statements are used to process data in an array, so the use of array in a program reduce size of the program.

  6. Types of array: • The are two types: • 1.One-dimensional array • 2.Multidimensional array

  7. One-dimensional array • Also known as a list or linear array. • Consists of only one column or one row. • E.g., array • array[0] • array[1] • . • . • array[4]

  8. The above array contain real type data. • It has five elements • The first element is array[0] that is in position 0 and the last element is array[4] that is in position 5-1=4.

  9. Declaring one-dimensional array: • Defining the name of the array, its type and the total number of elements of the array is called declaring of the array. • Syntax: • type array-name[n]; • Where ‘n’ is an unsigned integer value, represent the total number of elements of the array.

  10. E.g., • double temp[24]; • intabc[5]; • char name[15]; • etc

  11. Accessing data in one-dimensional array: • Each element of an array is referenced by its index. • In an array of n elements, each element has an index value. • The index of the first element is 0 and so on and index of the last element is n-1.

  12. Input/Output data in one-dimensional array: • Data is entered in an array using the input statement “cin” or “assignment” statements. • It is entered into individual elements of the array . • Separate input statement is used to enter data into each element of the array. • Similarly to print the data the output statements are used. The data from each individual element of the array is accessed.

  13. As similar input/output statement is used to access data in each element of the array, so the statement is written only once and a loop structure is used to repeat the input/output statement to access data of the element of the array. • Note : See examples(4.01—4.06)

  14. Initializing one-dimensional array: • The assigning of values to the elements of the array at the time of its declaration is called initializing of the array. • E.g., • double temp[4]={66.3, 23.2, 88.5, 45.6}; • Note: See examples(4.07—4.09)

  15. Multi-dimensional array: • A multi-dimensional array is an array of more than one array. • Two-dimensional array consists of columns and rows. • The index value of two-dimensional array consists of two subscripts. • One subscript represents the rows number and the second subscript represents the column number.

  16. Declaration of two-dimensional array: • A two dimensional array is declared by giving two indexed values enclosed in square brackets. • Syntax: • type array-name[r][c]; • e.g., intabc[5][3];

  17. Accessing data in two-dimensional array: • Data is entered into individual elements of a two-dimensional array. • To enter data, the element is referenced by its index or subscript value. • Similarly, data is retrieved from an array from individual elements of the array. • Note: See examples(4.15 & 4.16)

  18. Initializing Tables: • Assigning values to the elements of a table at the time of its declaration is called initializing of the table. • e.g., • intabc[2][3]={{3,4,5}{6,7,3}{2,8,9}}; • See example 4.17

  19. Initializing character type tables: • The values in a table of “char” type is also assigned in the same way as in int, float or double type tables. • e.g., char st[5][3]= {{‘a’, ‘x’, ‘y’}, • {‘p’, ’e’, ’t’}, • {‘p’, ‘a’, ‘k’}, • {‘a’, ‘b’, ‘c’}, • {‘3’, ‘1’, ‘6’}};

  20. Also: • char st[5][4]={“axy”, “pet”, “pak”, “abc”, • “316”}; • See example 4.18 • Here variable “st” can be treated as a string array. It has the capacity to store five strings each of 3 characters including null characters.

  21. Thus only two characters can be stored in each string and the null character is automatically inserted at the end. • ( END OF CHAPTER 04 )

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