Problem Solving and Program Design in C (5th Edition) by Jeri R. Hanly and Elliot B. Koffman

Problem Solving and Program Design in C

(5th Edition)

by Jeri R. Hanly and Elliot B. Koffman

CPCS 202Chapter 2 – Input/Output

12-10-1429

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CHAPTER 2 – Input / Output1. The Software

Development Method2. Variables3. Constants4. Output Operations and

Functions5. Input Operations and

Functions6. Using Comments7. Design / Algorithm Types8. Writing Program

Structure9. Changing the Display10.Types of Errors 2

#1. Hello World2. Get User ID3. Convert Miles to

Kilometers4. Finding the Value of the

Coins

column shows the topics index. column shows the programs index.

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The Software Development MethodA. Introduction

You need to be a problem solver A good problem solver a good programmer Programmers use the Software Development

Method This is what you will learn in this course.

B. Prototype

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ImplementationProblem Analysis Design /Algorithm Testing Maintenance

1. 2. 3. 4. 5. 6.

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C. ExampleThe Software Development Method

1. Problem:Your summer surveying job requires you to study some maps that give distances in kilometers and some that use miles. You and your coworkers prefer to deal in metric measurements. Write a program that performs the necessary conversion.


1. 2. 3. 4. 5. 6.

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The Software Development Method

2. Analysis (تحليل): 1. Problem Input: miles 2. Problem Output: kilometers 3. Relevant Formula: 1 mile = 1.609 kilometers


1. 2. 3. 4. 5. 6.

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C. Example

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3. Design / Algorithm: 1. Get the distance in miles from the user. 2. Convert the distance to kilometers. (1 kilometer = 1.609 miles) 3. Display the distance in kilometers on the screen.


1. 2. 3. 4. 5. 6.

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C. Example

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4. Implementation: (تنفيذ) Write the code.


1. 2. 3. 4. 5. 6.

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C. Example

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C. ExampleThe Software Development Method

5. Testing: 1. Verify that the program works properly. 2. Try few test cases. ( if the input is …, the output has to be … )


1. 2. 3. 4. 5. 6.

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6. Maintenance (صيانة): 1. Remove undetected errors. 2. Keep it up-to-date.


1. 2. 3. 4. 5. 6.

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C. Example

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Variables (متغير)Introduction

Store values in the memory under given names; these values can be changed

The types of the possible values called Data Types Choose good names for the variables:

No need to write any comment Easy to track Case sensitive Don’t use a Reserved Word

Three important stages in variables:1. Declaring a variable2. Initializing a variable3. Assigning a new value

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Data TypesNumbers only

Integerage = 36

Double \ Floatdegree = 36.4

Charactergender = ‘M’

The three data types showing are not all of the data types in C

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Variables – DeclaringA. Introduction

Each variable needs to be declared before using it Declaring a variable reserves space in the

memory Declaring variables has to be at the beginning of

functions (before writing any statement)B. Syntax

C. Example int id; double dollar; char gender; double tall, width, weight; 11

2

type variable_list ;

Data TypesNumbers

onlyInteger

(int)Doubl

e (doub

le)

Character

(char)

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Variables – InitializingA. Introduction

The first value for a variable called initialing a variable

You can not use a variable without initializing You can initial a variable at any place inside the

functionB. Syntax

C. Example id = 0750428; dollar = 3.75; gender = ‘M’; 12

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Expression could be a number or an equation

variable = expression ;

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Variables – Declaring & InitializingA. Introduction

You can save the space and the time by initializing a variable in the same time with declaring it

Again, this has to be at the beginning of functions before writing any statement

B. Syntax

C. Example int id = 0750428; double dollar = 3.75; char gender = ‘M’; 13

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type variable = expression ;


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Variables – AssigningA. Introduction

Changing the value of a variable called assigning a new value to the variable

B. Syntax

C. Example id = 0750428; dollar = 3.75; gender = ‘M’;

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variable = expression ;


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Declaring, Assigning, and InitializingConclusion 1

int id, age;

double dollar;

char gender = ‘d’;

id = 0750428;

dollar = 3.75;

age = 21;

dollar = 3.77;

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Decla

ring

Initi

alizi

ng

Assig

ning

Decla

ring

&As

signi

ng

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Tracking Variables in the MemoryConclusion 2

You can track the values of each variable in a table

The following program consists of 3 variables. The table tracks the values of each variable after executing each statement:1. X = 10;2. Z = 15.5;3. Y = X + Z;4. Y = Y + 1;5. Z = Y – 1.5 + 5;6. Z = Z / 2 + 5;7. X = Z % 3;

16The memory stores the last value of each variable

# X Y Z1. 102. 15.53. 25.54. 26.55. 306. 207. 2

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Constants (ثابت)A. Introduction

Store a value under a name The value of the constant can’t be changed

= You can’t assign a new value Constants require one stage only, which is

defining; it has to be at the begging of the program before writing ant function

Work with numbers onlyB. Syntax

C. Examples #define id 0750428 #define dollar 3.75 17

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#define variable value

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Output Operations and FunctionsA. Introduction

The output operations and functions will help you to display anything on the screen.

You can display some text only, a value of a variable only, or both.

In C language, you need to include the file stdio in order to use the function printf.

B. Syntax

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printf (format string);printf (format string, print list);

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Output Operations and FunctionsC. Examples

1. Display Hello… on the screen in C?use the function printfprintf(“Hello…”);

2. Display Hello… in 1st line and good in 2nd line?use the operation \nprintf(“Hello…\ngood”);

3. Display the value of the variable age; (if age is integer)?use the operation %d printf(“%d”, age);

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Output Operations and FunctionsC. Examples

4. Display the value of the variable X; (if X is double\float)? use the operation %fprintf(“%f”, X);

5. Display the value of the variable Y; (if Y is character)? use the operation %cprintf(“%c”, Y);

6. Display My age is then the value of the variable AGE?printf(“My age is %d”, AGE);

7. Display the variables age and GPA in one statement?printf(“I am %d years old, GPA: %f”, age, GPA);

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Output Operations and FunctionsD. Conclusion

The output operations and functions will help you to display text and/or the values of a group of variables on the screen. For examples: printf(“Enter the object mass in grams?”); printf(“%c”, first_init); printf(“I am %d years old.”, AGE);

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Input Operations and FunctionsA. Introduction

The input operations and functions will help you to get values for the variables from users.

You need to ask the user to input a value using the output function, then you can use the input function to get the value from the user.

In C language, you need to include the file stdio in order to use the function scanf.

B. Syntaxscanf (format string, input list);

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Input Operations and FunctionsC. Examples

1. Get the value for the variable X; (if X is integer)?use the operation %d scanf(“%d”, &X);

2. Get the value for the variable X; (if X is double\float)? use the operation %lf (Long Float) and not %f scanf(“%lf”, &X);

3. Get the value for the variable X; (if X is character)?use the operation %d scanf(“%c”, &X);

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Input Operations and FunctionsC. Examples

4. Get 3 characters from the user?scanf(“%c%c%c”, &first, &second, &third);

D. Conclusion The input operations and functions will help you to get a

value for a declared variable from the user. For examples: scanf(“%c%d”, &first_initial, &age);

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Using CommentsA. With your comments, it will easy to remember

the job of each statement in your program.B. Comment Types in C language:

Single-line: Start with the symbol // and end up with the end of the line

Single-line or Multi-lines: Start with /* and end up with */

C. Example:1. /* Name: Daniyal 2. ID: 707997 */3. double miles, kms;4. /* EXECUTABLE STATMENTS */5. printf(“Enter the distance in miles: “); // ask the user6. scanf(“%lf”, &miles); // get the miles

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Design/Algorithm Types Algorithm without variables:1. Get the distance in miles.2. Convert the distance to kilometers. (1 kilometer = 1.609 miles)3. Display the distance in kilometers.

Algorithm with variables:1. Get the value X (X: the distance in miles)2. Y = X / 1.609 (Y: the distance in kilo)3. Display the value Y

Algorithm with good variables’ names:1. Get the value TotalMiles2. TotalKilo = TotalMiles / 1.6093. Display the value TotalKilo

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Algorithms could write any way, but they have to be understandable

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Writing Program StructureA. Any group of statements needs to be

inside a function(Note: you will learn later more about functions and write more than one function)

B. The main function will be executed first1. /* include the header files here for any external

function, such as input/output functions */2. /* define any Constant (not Variable) here */3. int main (void)4. {5. /* Declare the variables here */6. /* Start writing the statements */7. return (0);8. }

you have to declare the variables at the beginning of any function 27

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Be Ready to Write a Program in

C

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Writing Program Structure

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C. Example

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Hello WorldA.Problem

We need a program that displays on the screen the text Hello World!!

B.Analysis Input Output

the text “Hello World!!” Formula

C.Design1. Display “Hello World!!” on the screen

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ImplementationProblem Analysis Design Outline Testing Maintenance

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#include <stdio.h>

int main(void){ // 1. Display “Hello World!!” on the screen printf(“Hello World!!\n”);

return(0);}

1.2.3.4.5.6.7.8.9.

Hello WorldD.Outline

E.Implementation

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#include <stdio.h>

int main(void){ // 1. Display “Hello World!!” on the screen

return(0);}

1.2.3.4.5.6.7.8.9.

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#include <stdio.h>

int main(void){ // 1. Display “Hello World!!” on the screen printf(“Hello World!!\n”);

return(0);}

1.2.3.4.5.6.7.8.9.

Hello WorldD.Outline

E.Implementation

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#include <stdio.h>

int main(void){ // 1. Display “Hello World!!” on the screen

return(0);}

1.2.3.4.5.6.7.8.9.

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Get User IDA.Problem

Write a program that gets the ID value from the userB.Analysis

Input ID

Output Formula

C.Design1. Get the ID from the user user_ID

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Put the value you get from the user in a

variable called user_ID

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Number of variables: 1This indicates that you need to declare 1 variable in the program

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Get User ID

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#include <stdio.h>

int main(void){ int user_ID;

// 1. Get the ID from the user

return(0);}

1.2.3.4.5.6.7.8.9.10.11.

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Get User ID

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DON’T try to get a value from a user (scanf) without asking (printf)


#include <stdio.h>

int main(void){ int user_ID;

// 1. Get the ID from the user printf(“Please enter your user ID: “); scanf(“%d”, user_ID);

return(0);}

1.2.3.4.5.6.7.8.9.10.11.12.

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Convert Miles to KilometersA.Problem

Your summer surveying job requires you to study some maps that give distances in kilometers and some that use miles. You and your coworkers prefer to deal in metric measurements. Write a program that performs the necessary conversion.

Each miles equal to 1.609 kilometer.

35Write the Analysis & Design for this problem?

3

Miles Kilometer


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Convert Miles to KilometersB.Analysis

Input KMS_PER_MILE = 1.609 Miles

Output Kilometers

Formula Kilometers = Miles x 1.609

C.Design1. Get the number of miles from the user miles2. Convert miles to kilometers:

kms = miles x KMS_PER_MILE3. Display the number of kilometers kms

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They are 2 variables in the Design, so 2 variables need to be declared

This input has a constant value

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Convert Miles to Kilometers

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/* Converts distances from miles to kilometers. */ #include <stdio.h> /* printf, scanf definitions */#define KMS_PER_MILE 1.609 /* conversion constant */ int main(void){ double miles, /* distance in miles */ kms; /* equivalent distance in kilometers */ /* 1. Get the number of miles from the user */ /* 2. Convert miles to kilometers */ /* 3. Display the number of kilometers */ return (0);}

1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.

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/* Converts distances from miles to kilometers. */ #include <stdio.h> /* printf, scanf definitions */#define KMS_PER_MILE 1.609 /* conversion constant */ int main(void){ double miles, /* distance in miles */ kms; /* equivalent distance in kilometers */ /* 1. Get the number of miles from the user */ scanf("%lf", &miles); printf("The distance in miles is %.2f.\n", miles); /* 2. Convert miles to kilometers */ kms = KMS_PER_MILE * miles; /* 3. Display the number of kilometers */ printf("That equals %.2f kilometers.\n", kms); return (0);}


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1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22. This program has a mistake that

may confuse any user, what is it?

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/* Converts distances from miles to kilometers. */ #include <stdio.h> /* printf, scanf definitions */#define KMS_PER_MILE 1.609 /* conversion constant */ int main(void){ double miles, /* distance in miles */ kms; /* equivalent distance in kilometers */ /* 1. Get the number of miles from the user */ scanf("%lf", &miles); printf("The distance in miles is %.2f.\n", miles); /* 2. Convert miles to kilometers */ kms = KMS_PER_MILE * miles; /* 3. Display the number of kilometers */ printf("That equals %.2f kilometers.\n", kms); return (0);}

1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.


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The programmer tries to get a value from the user without display any message on the screen to notify the user

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/* Converts distances from miles to kilometers. */ #include <stdio.h> /* printf, scanf definitions */#define KMS_PER_MILE 1.609 /* conversion constant */ int main(void){ double miles, /* distance in miles */ kms; /* equivalent distance in kilometers */ /* 1. Get the number of miles from the user */ printf("Please enter the value of distance in miles : "); scanf("%lf", &miles); printf("The distance in miles is %.2f.\n", miles); /* 2. Convert miles to kilometers */ kms = KMS_PER_MILE * miles; /* 3. Display the number of kilometers */ printf("That equals %.2f kilometers.\n", kms); return (0);}


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1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.

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/* Converts distances from miles to kilometers. */ #include <stdio.h> /* printf, scanf definitions */#define KMS_PER_MILE 1.609 /* conversion constant */ int main(void){ double miles, /* distance in miles */ kms; /* equivalent distance in kilometers */ /* 1. Get the number of miles from the user */ printf("Please enter the value of distance in miles : "); scanf("%lf", &miles); printf("The distance in miles is %.2f.\n", miles); /* 2. Convert miles to kilometers */ kms = KMS_PER_MILE * miles; /* 3. Display the number of kilometers */ printf("That equals %.2f kilometers.\n", kms); return (0);}

1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.


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Finding the Value of the CoinsA.Problem

We need a program that calculates the number of coins in a save box, and it displays the number of the dollars and the changes in cents.

USA Currency Coins: 1 quarter = 25 cents 1 dime = 10 cents 1 nickel = 5 cents 1 penny = 1 cent

For example: 10 quarters + 8 dimes + 1 nickels + 10 pennies

= (10 x 25) + (8 x 10) + (1 x 5) + (10 x 1)= 345 cents = 3 dollars and 45 cents

42Quiz: Write the Analysis & Design for this problem?

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Finding the Value of the CoinsB.Analysis

Input The count of quarters The count of dimes The count of nickels The count of pennies

Output The value in dollars The changes in cents

Formula 1 quarter = 25 cents 1 dime = 10 cents 1 nickel = 5 cents 1 penny = 1 cent

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Finding the Value of the CoinsC.Design (1st version)

1. Get the count of each kind of coin2. Find the value in dollars and change3. Display the value in dollars and the change

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C.Design (2nd version)1. Get the count of each kind of coin2. Compute the total value in cents3. Find the value in dollars and change4. Display the value in dollars and the change

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Finding the Value of the CoinsC.Design (3rd version)

1. Get the count of the quarters quarters2. Get the count of the dimes dimes3. Get the count of the nickels nickels4. Get the count of the pennies pennies5. Compute the total value in cents:

total_cents = quarters x 25 + dimes x 10 + nickels x 5 + pennies x 1

6. Find the value in dollars and change:dollars = total_cents / 100change = total_cents % 100

7. Display the value in dollars dollars8. Display the change change

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How many variables need to be declared? and what are their types?

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/* * Determines the value of a collecting of coins. */

#include <stdio.h>

int main(void){ int pennies, nickels; /* input - count of each coin type */ int dimes, quarters; /* input - count of each coin type */ int change; /* output - change amount */ int dollars; /* output - dollar amount */ int total_cents; /* total cents */

/* 1. Get the count of the quarters */ /* 2. Get the count of the dimes */ /* 3. Get the count of the nickels */ /* 4. Get the count of the pennies */ /* 5. Compute the total value in cents. */ /* 6. Find the value in dollars and change. */ /* 7. Display the value in dollars. */ /* 8. Display the change. */ return(0);}

Finding the Value of the Coins

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1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.

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/* * Determines the value of a collecting of coins.*/

#include <stdio.h>

int main(void){ int pennies, nickels; /* input- count of each coin type */ int dimes, quarters; /* input- count of each coin type */ int change; /* output- change amount */ int dollars; /* output- dollar amount */ int total_cents; /* total cents */

/* 1. Get the count of the quarters */ printf("Number of quarters> "); scanf("%d", &quarters);

/* 2. Get the count of the dimes */ printf("Number of dimes> "); scanf("%d", &dimes);


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41 dollar = 100 cents 1 quarter = 25 cents1 dime = 10 cents1 nickel = 5 cents1 penny = 1 cent


1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.

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/* 3. Get the count of the nickels */ printf("Number of nickels> "); scanf("%d", &nickels);

/* 4. Get the count of the pennies */ printf("Number of pennies> "); scanf("%d", &pennies);

/* 5. Compute the total value in cents. */ total_cents = 25 * quarters + 10 * dimes + 5 * nickels + pennies; /* 6. Find the value in dollars and change. */ dollars = total_cents / 100; change = total_cents % 100; /* 7. Display the value in dollars. 8. Display the change. */ printf("\nYour coins are worth %d dollars and %d cents.\n", dollars, change); return(0);}


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41 dollar = 100 cents 1 quarter = 25 cents1 dime = 10 cents1 nickel = 5 cents1 penny = 1 cent


23.24.25.26.27.28.29.30.31.32.

33.34.35.36.37.38.39.40.

41.42.43.

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Changing the Display - IntegerA. You can organize the display for integer

variables.B. Formats:

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Value

Format

Displayed Output

234 %4d ▒234234 %5d ▒▒234234 %6d ▒▒▒234234 %1d 234-234 %4d -234-234 %5d ▒-234-234 %6d ▒▒-234-234 %2d -234

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C. Example:1. printf(“ X Y\n”);2. printf(“---------\n”);3. printf(“%4d%4d\n”, 1, 2);4. printf(“%4d%4d\n”, 13, 6);5. printf(“%4d%4d\n”, 37, 513);

Run: X Y--------- 1 2 13 6 37 513

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Changing the Display - DoubleA. You can organize the display for double

variables.B. Formats:

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Value Format

Displayed Output

3.14159

%5.2f ▒3.14

3.14159

%3.2f 3.14

3.14159

%5.3f 3.142

3.14159

%5.1f ▒▒3.1

0.1234 %4.2f 0.12-0.006 %8.3f ▒▒-

0.006-0.006 %4.2f -0.01-0.006 %8.5f -0.00600-3.14159

%.4f -3.1416

Hint: think about the displayed output first, then write the format

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C. Example:1. double X, Y, Z;2. X = 10.23;3. Y = 102.235;4. Z = 20.2;5. printf(“>%6.2f\n”, X);6. printf(“>%6.2f\n”, Y);7. printf(“>%6.2f\n”, Z);

Run: 10.23102.24 20.20

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Types of Errors

• The program will not run until the error fixed.• e.g. missing a semicolon.

1. Syntax Error

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Types of Errors: Syntax Error

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.1.A pop-up window

will appear. CHOSE No to stop

the program.2.

Check the error message and the

line number

.3.Fix the error

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Questions1. The main different between the variables and

the constants in a program is:a) the value of the constant can be changed during

the programb) the value of the variable can be changed during

the programc) there is no difference between themd) none of the above is a correct statement

2. The codes at any function written in C language need to follow the following order:a) first, we write the executed statements. Then, we

declare the variablesb) first, we declare the variables. Then, we write the

executed statementsc) we can declare any variable at anyplace inside a

function-54-

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Questions3. Which of the following statements have a

syntax error:a) X = 10;b) Y = 20c) Z = 15.5;d) Y = X + Z;e) Y = Y + 1;f) Z = Y – 1.5 + 5;g) 23 = Z; h) Z = Z / 2 + 5;

-55-

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Homework1. Type Program 3 and run it, and display your

name and your ID at the beginning of the output ?(Take a copy of the code and a snapshot of the output of three different test cases, and then print them in ONE page only)

2. Track the memory in Program 4 ?(You need to show the code, the output of one test case, and tracking the memory in ONE page only; you can choose any input values)

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…

HANDWRITING IN THE HOMEWORK IS NOT ACCEPTABLE

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CHAPTER 2 – Input / Output1. The Software

Development Method2. Variables3. Constants4. Output Operations and

Functions5. Input Operations and

Functions6. Using Comments7. Design / Algorithm Types8. Writing Program

Structure9. Changing the Display10.Types of Errors 57

#1. Hello World2. Get User ID3. Convert Miles to

Kilometers4. Finding the Value of the

Coins

column shows the topics index. column shows the programs index.

Problem Solving and Program Design in C (5th Edition) by Jeri R. Hanly and Elliot B. Koffman

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Transcript of Problem Solving and Program Design in C (5th Edition) by Jeri R. Hanly and Elliot B. Koffman