CSE 100

Common Programming Errors Assignment Statements

Incrementing & Decrementing

How many bytes?#include <iostream.h>void main (){ // the columns below are just for showing on one screen char ch; float num4; unsigned int num3; int num1; double num5; long int num2; long num6;

cout <<"\nBytes of storage used by a character:\t\t\t " <<sizeof(ch) <<"\nBytes used by integer:\t\t\t " <<sizeof(num1) <<"\nBytes used by long integer:\t\t " <<sizeof(num2) <<"\nBytes used by unsigned integer:\t\t " <<sizeof(num3) <<"\nBytes used by floating point number:\t " <<sizeof(num4) <<"\nBytes used by double floating point:\t " <<sizeof(num5) <<"\nBytes used by long floating point:\t\t " <<sizeof(num6)<<‘\n’; }

How many bytes?

Bytes of storage used by a character: 1

Bytes used by an integer: 4

Bytes used by a long integer: 4

Bytes used by an unsigned integer: 4

Bytes used by a floating point number: 4

Bytes used by a double floating point: 8

Bytes used by a long floating point: 4

Assignment Operator

The assignment operator (=)causes the operand on the left to take on the value to the right side of the statement.

This operator assigns from right to left.

valid invalid riker = 5.6 5 = riker

*

Assignment Statement

Syntax: variable = value;variable = value;

Examples:compputer = “dumb”;Al_E_Newman = “dumber”;count = count +1;

*

Assignment Example 1

#include <iostream.h>#include <iostream.h>void main(void)void main(void){{ int sum;int sum;

sum = 25;sum = 25; cout << “The number stored in sum is " cout << “The number stored in sum is "

<< sum;<< sum; sum = sum + 10;sum = sum + 10; cout << "\nThe number now stored in sum is " cout << "\nThe number now stored in sum is "

<< sum<< ‘\n’; << sum<< ‘\n’;}

Assignment Example 1

Output:

The number stored in sum is 25

The number now stored in sum is 35

_ Press any key to continue

Assignment Example 2int sum;int sum;

sum = 0;sum = 0;cout << "\nThe value of sum is initially set to " << sum;cout << "\nThe value of sum is initially set to " << sum;sum = sum + 96;sum = sum + 96;cout << "\nsum is now " << sum;cout << "\nsum is now " << sum;sum = sum + 70;sum = sum + 70;cout << "\nsum is now " << sum;cout << "\nsum is now " << sum;sum = sum + 85;sum = sum + 85;cout << "\nsum is now " << sum;cout << "\nsum is now " << sum;sum = sum + 60;sum = sum + 60;cout << "\nThe final sum is " << sum;cout << "\nThe final sum is " << sum;

Assignment Example 2

Output:

The value of sum is initially set to 0

sum is now 96

sum is now 166

sum is now 251

The final sum is 311

Practice Assignment

An aquarium consists of four panels, all of which are metal except for the largest which is glass. All three side panels are rectangles. The bottom panel is a right triangle. There is no top panel. After getting user input on the dimension, calculate the area of the glass panel.

Assume the user enters positive real numbers expressed in inches. Comments are not required.

sample outputHeight: [10.0]Width: [9.0]Length: [12]The glass is 150.0 square inches.Press any key to continue._

Practice Assignment

Assignment Operators

A shorthand notation for certain assignments.

They all have right-to-left associativity.

variable op= (expression)

is equivalent to

variable = variable op (expression)

+= add then assign-= subtract then assign

*= multiply then assign

/= divide then assign

X -= 3 X = X - 3

pay *= 0.35 pay = pay * 0.35

Assignment Operators

Assignment Operators

+= -= *= /= %=1. i += 2 i = i + 22. r *= 7 r = r * 73. j *= (k + 3) j = j * (k + 3)

4. x /= y - 4 x = x /y - 45. hour %= 12 hour = hour % 126. left -= t_out left = left - t_out

Assignment Operators

* *

Subtotals

Syntax: variable = variable + variable = variable + new_value;new_value;

Examplesyear_pay = year_pay + pay;balance = balance - debit;counter = counter + 1;counter += 1;

*

} same

Increment/Decrement

++ increment

-- decrement

uniary operators

take a single operand

ex. num++num++, num--num--

++num++num, --num--num

Increment/Decrement

k = k + 1 k = k + 3

k += 1 k += 3

k ++ no equivalent

Increment/Decrement

num = num + 1num = num + 1

num++num++

i = i + 1i = i + 1

i++i++

num = num - 1num = num - 1

num--num--

i = i - 1i = i - 1

i--i--

* * ** *

num += 1num += 1 num num --=1=1

i += 1 i += 1 i i --= 1= 1

Increment/Decrementvalue after execution

kk g g

1. k = 7;

2. g = 2;

3. k = g;

4. g = g + 1;

7 %#@$

7 2

2 2

2 3

* * ** *

or combineor combine 3 & 4 3 & 4

k = g++k = g++

Increment/Decrement

postfix:postfix: first use it, then alter valuefirst use it, then alter value

z = 10;

v = z--;

cout <<v<<‘\t’<<z;

v z

10 9

count = 10;

k = count++;

cout<<k<<‘\t’<<count;

k count

10 11

* * * *

or combineor combine 3 & 4 3 & 4

k = ++gk = ++g

Increment/Decrementvalue after execution

kk g g

1. k = 7;

2. g = 2;

3. g = g + 1;

4. k = g;

7 %#@$

7 2

7 3

3 3

* * ** *

Increment/Decrement

prefix:prefix: first alter value, then use itfirst alter value, then use it

z = 10;

v = --z;

cout <<v<<‘\t’<<z;

v z

9 9

count = 10;

k = ++count;

cout<<k<<‘\t’<<count;

k count

11 11

* * * *

outputoutput

11 cout << cnt++<<'\n';cout << cnt++<<'\n';

22 cout<<cnt<<'\n';cout<<cnt<<'\n';

33 cout<<(cnt++==guess)<<'\n';cout<<(cnt++==guess)<<'\n';

44 cout<<cnt<<'\n';cout<<cnt<<'\n';

55 cout<<cnt++<<'\n';cout<<cnt++<<'\n';

66 cout<<cnt<< '\n'<<'\n';cout<<cnt<< '\n'<<'\n';

Increment/Decrement

* * ** * *

10 // print then inc// print then inc

11

1 // check then inc// check then inc

12

12

13

int cnt = 10, guess = 11;int cnt = 10, guess = 11;

outputoutput

11 cout << ++cnt<<'\n';cout << ++cnt<<'\n';

22 cout<<cnt<<'\n';cout<<cnt<<'\n';

33 cout<<(++cnt==guess)<<'\n';cout<<(++cnt==guess)<<'\n';

44 cout<<cnt<<'\n';cout<<cnt<<'\n';

55 cout<<++cnt<<'\n';cout<<++cnt<<'\n';

66 cout<<cnt<< '\n'<<'\n';cout<<cnt<< '\n'<<'\n';

Increment/Decrement

* * ** * *

11 // inc then print// inc then print

11

0 // inc then check// inc then check

12

13

13

int cnt = 10, guess = 11;int cnt = 10, guess = 11;

Area of Circle -- 1

double radius = 5, area;

const double PI = 3.1416;

area = PI * radius * radius;cout << "The area of a circle of radius ” << radius << " is "<< area <<"\n";

* *

Area of Circle -- 1

Output:

The area of a circle of radius 5 is 78.54

ºF - ºC Conversion -- 1

double celsius, faren;

faren = 98.6;

celsius = 5.0/9.0 * (faren - 32.0);

cout << faren <<" degrees Fahrenheit equals "

<< celsius <<" degrees celsius.\n";

ºF - ºC Conversion -- 1

Output:

98.6 degrees Fahrenheit equals 37 degrees celsius.

Increment/Decrementa) cout << j++

b) cout << ++j

c) cout << j += 14

d) cout << j /= 10

e) cout << j *= 10

f) cout << j -= 6

g) cout << (j = 5) + j

h) cout << (j == 5) + j* * * ** * * *

int j = 5;int j = 5;

a)a) 5

b)b) 6

c)c) 19

d)d) 0

e)e) 50

f) f) -1

g) g) 10

h) h) 6

Common Programming ErrorsCommon Programming Errors

not declaring all variables

storing data of one type in a variable of a different type. The variable data type is kept.

using a variable before assigning it a value

mixing data types in an operation

in integer division 4/5 = 0

MoreCommon Programming Errors

forgetting <<<< and ;;

not initializing variables before use

applying ++++ or ---- to an expression

forgetting >>>> to separate variables in cin

dummy box for extra sound

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““Except in Except in C++C++ class” class”Joseph DeLibero