Problem Solving and Program Design in C

(5th Edition)

by Jeri R. Hanly and Elliot B. Koffman

CP 202Chapter 8

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CHAPTER 8 - ArraysChapter 8

1. Arrays1a.

Declaring

1b. Manipulating

1c. Declaring and Initializing

2. Arrays and Loops

3. Arrays and Pointers

4. Arrays and Functions

4a. Arrays as Output

Arguments

4b. Arrays as Input Arguments

5. Multidimensional Arrays

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ArraysA. Introduction

An array is a collection of two or more adjacent memory cells that are associated with a particular symbolic name.

B.Subtopics Declaring arrays Manipulating arrays Declaring and initializing arrays

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DeclaringA. Introduction

Declaring arrays is similar to declaring variables, but declaring arrays requires declaring the name of the array and the number of the cells associated with it.

B.Syntax

C.Example int id[3]; double dollar[5]; char gender[2];

Data TypesNumbers

onlyInteger

(int)Doubl

e (double)

Character

(char)type array_name[size] ;

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Manipulating

Explanation StatementDisplays the value of x[0], which is 16.0. printf(“%.1f”, x[0]);

Stores the value 25.0 in x[3]. x[3] = 25.0;

Stores the sum of x[0] and x[1], which is 28.0 in the variable sum.

sum = x[0] + x[1];

Adds x[2] to sum. The new sum is 34.0. sum += x[2];

Adds 1.0 to x[3]. The new x[3] is 26.0. x[3] += 1.0;

Stores the sum of x[0] and x[1] in x[2].The new x[2] is 28.0.

x[2] = x[0] + x[1];

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ManipulatingExplanation Statement

i = 5;

Displays 4 and 2.5 ( value of x[4]) printf(“%d %.1f”, 4, x[4]);

Displays 5 and 12.0 ( value of x[5]) printf(“%d %.1f”, i, x[i]);

Displays 13.0 ( value of x[5] plus1) printf(“%.1f”, x[i] +1);

Displays 17.0 ( value of x[5] plus5) printf(“%.1f”, x[i] +i);

Displays14.0 ( value of x[6]) printf(“%.1f”, x[i +1]);

Invalid. Attempt to display x[10] printf(“%.1f”, x[i +i]);

Invalid. Attempt to display x[10] printf(“%.1f”, x[2 * i]);

Displays -54.5 ( value of x[7]) printf(“%.1f”, x[2 * i-3]);

Displays 6.0 ( value of x[2]) printf(“%.1f”, x[(int) x[4]]);

Displays12.0 ( value of x[5]); then assign 6 to I printf (“%.1f”, x[i++]);

Assigns 5(6-1) to i and then displays 12.0 (value of x[5]) printf (“%.1f”, x[--i]);

Assigns 12.0 (value of x[5]) to x[4] x[ i – 1] = x[i];

Assigns 14.0 (value of x[6]) to x[5] x[i] = x[i+1];

Illegal assignment statement x[i] – 1 = x[i];

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Declaring and InitializingA. Introduction

Arrays can be initialized when they are declared as same as variables

B.Example int prime[] = {2, 3, 5, 7, 11, 13, 17, 19}; char vowels[] = {‘A’, ‘E’, ‘I’, ‘O’, ‘U’};

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Arrays and LoopsA. Introduction

If you wish to process the elements of an array in sequence, you can use loop

Note: any array starts with element zero (not one)B.Example

Write a fragment of a program that stores the squares of the integers 0 through 9 ?

int square[10], i;for (i=0; i<10; ++i)

square[i] = i * i;

0 1 4 9 16 25 36 49 64 81[0] [1] [2] [3] [4] [5] [6] [7] [8] [9]

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Calculating Mean and SD Write a program that computes the mean and

standard deviation of an array of data and displays the difference between each value and the mean.

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Calculating Mean and SD 1

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Calculating Mean and SD 1

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Arrays and PointersA.Without arrays:int andy, *ted;andy = 25;fred = andy;ted = &andy;

B.With arrays:char andy[]={‘a’,‘b’,‘c’};char fred[3];char *ted;fred[0] = andy[0];fred[1] = andy[1];fred[2] = andy[2];ted = andy;

1775 1776 1777 1778 1779

‘b’

andy

‘a’ ‘c’

[0] [1] [2]

‘b’

fred

‘a’ ‘c’

[0] [1] [2] 1776

ted

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Tutorialint main (void) {

char letters[5], char *p;int n;p = letters; *p = ‘a’; // ≡ letters[0]=‘a’p++;*p = ‘b’; // ≡ letters[1]=‘b’p = &letters[2]; *p = ‘c’; // ≡ letters[2]=‘c’p = letters + 3; *p = ‘d’; // ≡ letters[3]=‘d’p = letters; *(p+4) = ‘e’; // ≡ letters[4]=‘e’ for (n=0; n<5; n++)

printf(“%c”, letters[n]);return (0);

}

letters

[0] [1] [2] [3] [4]

*p

‘b’‘a’ ‘c’ ‘d’ ‘e’

Way

1W

ay 2

Way

3W

ay 4

Way

5no

po

inte

r

1775 1776 1777 1778 1779

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Arrays and FunctionsA. Introduction

Previous examples in functions show that the arguments are variables, so changing their values inside the functions will not affect the original values in the main function

However, using pointers allows you to send the address of a variable instead of the value of a variable, so the changing will take affect

Sending an array as an argument requires sending the address of the first element in the array

B.Subtopics Arrays as output arguments Arrays as input arguments

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Arrays as Output ArgumentsA. Introduction

In simple (not array) parameters:void test(int *list) {

*list = 10;}int main(void) {

int x;test(&x);

} In array parameters:void test(int *list) {

*(list+5) = 10;}int main(void) {

int x[10];test(&x[0]);

}

or test(int list[])

or test(x)

or list[5] = 10;

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Arrays as Output ArgumentsB.Example

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Arrays as Input ArgumentsA. Introduction

In simple (not array) parameters:void function test(int list) {

:}int main(void) {

int x;test(x);

} In array parameters:void test(const int *list) {

:}int main(void) {

int x[10];test(&x[0]);

}

or test(

const in

t list[]

)

or test(x)

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Arrays as Input ArgumentsB.Example

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Arrays and FunctionsC.Example

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Simulating Stacks A stack is a data structure in which only the

top element can be accessed.

Inserting a new element at the top of a stack is called push.

Removing the top element of a stack is called pop.

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Simulating Stacks

Write the main() function for this program?

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Array Search - Linear Search Search for a value inside an array. The simple process is to check each element

in the array using a loop and exit the loop if the value is found or you finished checking all the elements. This process is called a linear search.

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Array Search - Linear Search 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.

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Array Search - Linear Search 3

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Sorting an Array Start from the first

data element until the previous of the last one and do the following:

Search for the smallest element from the current data element until the last one [subarray]. If you find one,

exchange it with the current data element.

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Sorting an Array 4

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Multidimensional Arrays Multi-dimensional arrays are arrays with two

or more dimensions. Example of two dimensions:

Example of three dimensions: int cube[100][5][4];cube[0][2][3] = 2;

char jimmy[3][5];

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Declaring and Initializing One Dimension arrays:

int prime[] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29};

char vowels[] = {‘A’, ‘E’, ‘I’, ‘O’, ‘U’};

Two Dimensions arrays:

int words[2][3] = { {‘a’,’n’,’d’}, {‘o’,’r’,’ ’}};

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Tic-Tac-Toe Write a function to check whether a tic-tac-toe

board is completely filled, assuming the original value for each cell is one space?

ttt_brd[1][2]

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Tic-Tac-ToeImplementationProblem Analysis Design Outline Testing Maintenance

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Enrollment Data in 3D Assuming that you have three-dimensional

array, called enroll, that may be used to store the enrollment data for a college.

The college offers 100 courses at five different campuses. We will number the freshman year 0, the sophomore year 1,… 3

Write the code for: Display number of students in each course Display number of students at each campus

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Enrollment Data in 3D// Display number of students in each coursefor (course = 0; course < 100; course++) {

course_sum = 0;for (campus = 0; campus < 5; campus++) {

for (cls_rank = 0; cls_rank < 4; cls_rank++) {

course_sum += enroll[course][campus][cls_rank];

}}printf(“Number of students in course %d is %d\

n”, course, course_sum);

}

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Enrollment Data in 3D// Display number of students at each campusfor (campus = 0; campus < 5; campus++) {

campus_sum = 0;for (course = 0; course < 100; course++) {

for (cls_rank = 0; cls_rank < 4; cls_rank++) {

campus_sum += enroll[course][campus][cls_rank];

}}printf(“Number of students at campus %d is %d\

n”, campus, campus_sum);}

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CHAPTER 8 - ArraysChapter 8

1. Arrays1a.

Declaring

1b. Manipulating

1c. Declaring and Initializing

2. Arrays and Loops

3. Arrays and Pointers

4. Arrays and Functions

4a. Arrays as Output

Arguments

4b. Arrays as Input Arguments

5. Multidimensional Arrays

C