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CS 1430: Programming in C++

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Literal Values

Literal values of int 5 0 -100

Literal values of float 3.1415926 0.0 -12.5

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Positive, Negative, and Zero

Is 0 positive or negative? 0 is neither positive nor negative.

-2 -1 0 1 2

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Literal Values (II)

Literal values of char

‘C’

‘A’

‘D’

Literal values of string

“Enter an integer: ”

“Your Grade is ”

“A”

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Variables// Variables can have initial valuesint num1, total = 0;

// Variables can have different values cin >> num1;

num1 = 58;

total = total + num1;

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Symbolic Constants// Symbolic constantconst int MAX_SCORE = 60; // Must give a value// Store in memory

// Can we do this?

MAX_SCORE = 100;

cin >> MAX_SCORE;

// Error: constant cannot change its value

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No Magic Numbers// Define symbolic constantconst int MAX_SCORE = 60;

int myScore;

myScore = 60; // Is this good?// NO!// Magic number!// Half points off!

myScore = MAX_SCORE;// Very good!

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The Cast Functionsint num1, num2; float quotient;

cin >> num1 >> num2; //No input prompt!// 3 5quotient = num1 / num2; // what’s the value of quotient?

// How to get float quotient?quotient = float(num1) / num2;// Use cast function.// coercion

quotient = float(num1 / num2);// Integer division or float division?// Integer division!

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The IF statementint num1, num2; float quotient;

cin >> num1 >> num2;

quotient = float(num1) / num2;// Any possible issues?

// What if num2 is zero? if (num2 != 0) quotient = float(num1) / num2;

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The IF statementint num1, num2; float quotient;

. . .

if (num2 != 0) quotient = float(num1) / num2;

// Semantics// do computation only when num2 is not zero// the statement is skipped when num2 is zero// Syntax// condition inside ()// != for not equal// Style// on separate lines// indent 3 spaces

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If-Elseif (num2 == 0)

cout << endl << "Cannot divide by zero!";

else

{

quotient = float(num1) / num2;

cout << endl

<< "The quotient is " << quotient << ‘.’;

}

// Semantics// do different things when num2 is zero or not// Syntax// braces for multiple statements (statement block)// == for equal// Why use “==” instead of “=”?// Style// braces on separate lines

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If-Elseif (num2 == 0)

{

cout << endl << "Cannot divide by zero!";

}

else

{

quotient = float(num1) / num2;

cout << endl

<< "The quotient is " << quotient << ‘.’;

}

// Syntax// braces are optional for single statement

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Statement Blockif (num2 == 0) cout << endl << "Cannot divide by zero!"; else quotient = float(num1) / num2; cout << endl << "The quotient is " << quotient;

// Will the program do output when num2 is 0?// YES!// Same as the following:if (num2 == 0) cout << endl << "Cannot divide by zero!"; else quotient = float(num1) / num2;

cout << endl << "The quotient is " << quotient;

// Indentation and blank line is a style issue // It does not make a block

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If-Elseif (num2 == 0)

{

cout << endl << "Cannot divide by zero!";

}

else

{

quotient = float(num1) / num2;

cout << endl

<< "The quotient is " << quotient << ‘.’;

}

// Syntax// braces are optional for blocks of single statement// braces are required for blocks of multiple statements

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Comparison Operators

==

!=

>

>=

<

<=

No Space between!

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Logical Operators

&& // And

|| // Or

! // Not

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Comparison Operators!=

!>

// NO!

<=

// Yes!

≤

// NO!

<=

// Yes!

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Comparing characters

const char UPPER_A = 'A';

char inputChar;

cout << endl << "Enter a char: ”;

cin >> inputChar;

if (inputChar == UPPER_A)

cout << endl << “It's an A!”;

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Examples

if (inputChar >= UPPER_A && inputChar <= 'Z') cout << endl // What should be the message? << "It's an upper case letter.";

inputChar = ‘C'; inputChar = inputChar + 1; cout << endl << "The next char is " << inputChar; // The next char is D

inputChar = ‘C'; cout << endl << "The next value is " << inputChar + 1; // The next value is 68

cout << endl << "The next char is " << char(inputChar + 1); // The next char is D

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Multiple Conditions

int num1, num2;

cin >> num1 >> num2;

if (num1 > 0 && num2 > 0) cout << “Both numbers are positive.” << endl;

if (num1 > 0 || num2 > 0) cout << “At least one number is positive.” << endl;

if (num1 && num2 == 0) cout << “\nBoth numbers are zero.”;// NO!

if (num1 == 0 && num2 == 0) cout << “\nBoth numbers are zero.”;// Good!

if (num1 = 0 && num2 = 0) cout << “\nBoth numbers are zero.”;// NO!// “=” is assignment!

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Checking Input

int score1, score2;

Cout << “Enter two scores between 0 and 60, inclusive.”;cin >> score1 >> score2;

if (score1 >= 0 && score1 <= 60 && score2 >= 0 && score2 <= 60) cout << “Both numbers are in the range.” << endl;

// Magic numbers!

const int MAX_SCORE = 60;const int MIN_SCORE = 0;

if (score1 >= MIN_SCORE && <= MAX_SCORE && score2 >= MIN_SCORE && score2 <= MAX_SCORE) cout << “Both numbers are in the range.” << endl;

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Example: Find the MAX of two numbers

int num1, num2, max;

cin >> num1 >> num2;

if (num1 > num2) max = num1; else max = num2;

cout << “The max value is ” << max << endl;

// Another wayif (num1 >= num2) max = num1; else max = num2;

cout << “The max value is ” << max << endl;

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Positive or Non-Positive

int x = 10, y = 7;float z = -5.0;

z = y / x; z = y / float(x);

if (z > 0) cout << “Positive."; else cout << "Non-Positive.";

// what is the output?

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Even and Odd Numbers

const int EVEN_NUMBER_DIVIDER = 2;

int theNum;

cout << "Enter an integer: "; cin >> theNum;

// How do we know an integer is an even number?// The remainder operator %!if ((theNum % EVEN_NUMBER_DIVIDER) == 0) cout << theNum << " is an even number."; else cout << theNum << " is an odd number.";

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Square Root Function

float theNum;

cout << "Enter a number: "; cin >> theNum;

// How do we compute the square root of a number?// Call function sqrt()!if (theNum >= 0) cout << “The square root of ” << theNum << “ is ” << sqrt(theNum); else cout << theNum << " is a negative number.";

// Need to include header file <cmath>

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Power Function#include <iostream>#include <cmath>

using namespace std;

int main(){ float base, expo;

cout << "Enter two numbers: "; cin >> base >> expo;

// How do we compute baseexpo

// Call function pow()! if (base > 0) cout << “Base ” << base << “ raised to power ” << expo << “ is ” << pow(base, expo); else cout << “Base is not positive.";

return 0;}

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Quiz 1-3

1 point

Submit to the Grader

Differences: NONE

Due 5 PM, today

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Quiz 2-1

1 point

Submit to the Grader

Differences: NONE

Due 5 PM, Monday

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Where Are the Materials?

Labs/ProgsK:\Courses\CSSE\CourseFiles\CS1430

https://xray.ion.uwplatt.edu/Files/

Notes/QuizzesSection Home Page:

http://people.uwplatt.edu/~yangq/cs143/

Your ScoresDesire2Learn

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