Chapter 8 Arrays Part II J. H. Wang ( 王正豪 ), Ph. D. Assistant Professor Dept. Computer Science...

Chapter 8ArraysPart II

J. H. Wang (王正豪 ), Ph. D.

Assistant Professor

Dept. Computer Science and Information Engineering

National Taipei University of Technology

Copyright ©2004 Pearson Addison-Wesley. All rights reserved. 8-2

Stacks

• A stack is a data structure in which only the top element can be accessed.

• pop remove the top element of a stack

• push insert a new element at the top of the stack


Stacks (Cont’d)

• Example– char s[STACK_SIZE]; /* a stack of characters */– int s_top = -1; /* stack s is empty */– max_size: STACK_SIZE– STACK_EMPTY: a previously defined constant

macro


Figure 8.14 Functions push and pop


Figure 8.14 Functions push and pop (cont’d)


Stack Exercise

• Implement a program to output the input data in reverse order by stack.– For example, input

a b c d ewill output

e d c b a


Searching an Array

• Target search

• Linear search


Linear Search Algorithm

– Assume the target has not been found.– Start with the initial array element.

– repeat while the target is not found and there are more array elements

• if the current element matches the target– Set a flag to indicate that the target has been found.

• else– Advance to the next array element.

– if the target was found• Return the target index as the search result.

– else• Return -1 as the search result.


Figure 8.15 Function That Searches for a Target Value in an Array


Exercise

• How to find ALL elements which match the target?


Sorting an Array

• Selection sort

• ALGORITHM FOR SELECTION SORT– for each value of fill from 0 to n-2

• Find index_of_min, the index of the smallest element in the unsorted subarray list[fill] through list[n-1].

• if fill is not the position of the smallest element (index_of_min)

– Exchange the smallest element with the one at position fill.


Figure 8.16 Trace of Selection Sort


Figure 8.17 Function select_sort


Exercise

• Implement the function get_min_range.


Multidimensional Arrays

• Multidimensional array an array with two or more dimensions

• char tictac[3][3];

]


Multidimensional Arrays (Cont’d)

• In the declaration of a multidimensional array function parameter, only the first dimension, the number of rows, can be omitted.– char tictac[ ][3]


Figure 8.19 Function to Check Whether Tic-tac-toe Board Is Filled


Exercise

• Implement a Tic-Tac-Toe game, allowing to users to play in turn. This program will judge which one is winner.


Initialization of Multidimensional Arrays

• char tictac[3][3] = { {' ', ' ', ' '}, {' ', ' ', ' '}, {' ', ' ', ' '} };


Arrays with Several Dimensions

• assume that the college offers 100 (MAXCRS) courses at five different campuses for each grade of students

• be aware of the amount of memory space required by each large array in a program


Figure 8.20 Three-Dimensional Array enroll


Arrays with Several Dimensions (Cont’d)


Exercise

• Print the number of enrolled students for each grade.


Common Programming Errors

• subscript-range error.– int celsius[100];– Reference to celsius[150] may cause an error

message such as:• access violation at line no. 28

– In many situations, however, no run-time error message will be produced

– entirely the responsibility of the programmer


Common Programming Errors (Cont’d)

• Range for both the initial and the final values of the loop control variable.

• When using arrays as arguments to functions, be careful not to apply the address-of operator to just the array name.– Consider &celsius[10] and &celsius

• Use int z[ ] for array parameters to assist readers of your code.


Figure 8.21 Sales Analysis Output


Figure 8.22 Sales Analysis Main Function


Figure 8.23 Function scan_table and Helper Function initialize


Figure 8.23 Function scan_table and Helper Function initialize (cont’d)


Figure 8.24 Function display_table and Helper Function display_quarter


Figure 8.24 Function display_table and Helper Function display_quarter (cont’d)

Chapter 8 Arrays Part II J. H. Wang ( 王正豪 ), Ph. D. Assistant Professor Dept. Computer Science...

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