The document summarizes key concepts from a lecture on computer applications in industrial engineering, including: - Floating point numbers have limited precision that varies by type (e.g. float has 7 digits, double has 15-16 digits). - Arithmetic operators in C# include addition, subtraction, multiplication, division, and modulus. - Relational operators compare values and return true or false, while logical operators combine conditional tests. - Decision structures like if, else if, else and switch statements allow conditionally executing blocks of code.

1. DR ATIF SHAHZAD
Computer Applications
in Industrial Engg.-I
IE-322
LECTURE #03

2. Computer Applications in
Industrial Engg.-I
IE322

3. …Recap
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4. What we will see…
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Arithmetic Operators & Precedence
Relational Operators
Increment Operator
Prefix & Postfix Notations
Comparison and Logical Operators
The if Statement
The if-else Statement
Nested if Statements
The switch-case Statement

5. A random review
IE322

6. Floating point numbers
float
• 4 Bytes
• 7 digit precision
double
• 8 Bytes
• 15-16 digit precision
decimal
• 16 Bytes
• 28-29 digit precision
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±1.5×10-45 ±3.4×1038
±5.0×10-324 ±1.7×10308
±1.0×10-28 ±7.9×1028

7. Floating point numbers
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static void Main(string[] args)
{
float f_no = 0.0f;
double d_no = 0.0d;
decimal m_no = 0.0m;
f_no = 1 / 3f;
d_no = 1 / 3d;
m_no = 1 / 3m;
//place holder
Console.WriteLine("Float no. is {0}", f_no);
Console.WriteLine("Double no. is {0}", d_no);
Console.WriteLine("Decimal no. is {0}", m_no);
}

8. ReadLine()
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Console.WriteLine("What is your name?");
string name = Console.ReadLine();
Console.WriteLine("Welcome " + name + ", welcome back!");

9. Arithmetic Operators
IE322

10. Arithmetic Operators
* /
% +
-
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11. Operators Precedence Example
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Write the expression in c#
z=pr%q + w/x-y
𝑧 = 𝑝 × 𝑟 %𝑞 +
𝑤
𝑥
− 𝑦

12. Problem
Write a program that enters the
coefficients a, b and c of a quadratic
equation
𝑎𝑥2
+ 𝑏𝑥 + 𝑐 = 0
and calculates and prints its real roots.
Note that quadratic equations may have 0, 1 or
2 real roots.
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13. Math Library
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Math.Sqrt(56);
Math.Pow(b,2);// for 𝑏2
Math.Sqrt(Math.Pow(b,2)-4*a*c); // Discriminant

14. Other Operators
IE322

15. Relational Operators
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Operator Notation in C#
Equals ==
Not Equals !=
GreaterThan >
GreaterThan or Equals >=
LessThan <
LessThan or Equals <=
bool result = 5 <= 6;
Console.WriteLine(result); //True

16. Increment (Decrement) Operator
x=6;
x = x + 1;
x = x++;
x += 1; //CompoundAssignment
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x /= 4; // equivalent to x=x/4;
x *= 8; // equivalent to x=x*8;
x %= 2; // equivalent to x=x%2;

17. Prefix & Postfix form
++x; //prefix
x++; //postfix
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int x = 3;
int y = ++x;
// x is 4 and y is 4
int x = 3;
int y = x++;
// x is 4 and y is 3

18. Prefix & Postfix form
++x; //prefix
x++; //postfix
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int x = 3;
int y = ++x;
// x is 4 and y is 4
int x = 3;
int y = x++;
// x is 4 and y is 3

19. Logical Operators
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Operator Notation in C#
Logical NOT !
LogicalAND &&
Logical OR ||
Logical Exclusive OR (XOR) ^

20. Decision Structures
IE322

21. if statement
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if (condition)
{
statements;
}
static void Main()
{
Console.WriteLine("Enter two numbers.");
int biggerNumber = int.Parse(Console.ReadLine());
int smallerNumber = int.Parse(Console.ReadLine());
if (smallerNumber > biggerNumber)
{
biggerNumber = smallerNumber;
}
Console.WriteLine("The greater number is: {0}",
biggerNumber);
}

22. if else statement
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if (expression)
{
statement1;
}
else
{
statement2;
} string s = Console.ReadLine();
int number = int.Parse(s);
if (number % 2 == 0)
{
Console.WriteLine("This number is even.");
}
else
{
Console.WriteLine("This number is odd.");
}

23. Nested if else statements
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if (expression)
{
if (expression)
{
statement;
}
else
{
statement;
}
}
else
statement;
if (first == second)
{
Console.WriteLine(
"These two numbers are equal.");
}
else
{
if (first > second)
{
Console.WriteLine(
"The first number is bigger.");
}
else
{
Console.WriteLine("The second is bigger.");
}
}

24. if else if statements
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int ch = 'X';
if (ch == 'A' || ch == 'a')
{
Console.WriteLine("Vowel [ei]");
}
else if (ch == 'E' || ch == 'e')
{
Console.WriteLine("Vowel [i:]");
}
else if …
else …

25. Switch case statement
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switch (day)
{
case 1: Console.WriteLine("Monday"); break;
case 2: Console.WriteLine("Tuesday"); break;
case 3: Console.WriteLine("Wednesday"); break;
case 4: Console.WriteLine("Thursday"); break;
case 5: Console.WriteLine("Friday"); break;
case 6: Console.WriteLine("Saturday"); break;
case 7: Console.WriteLine("Sunday"); break;
default: Console.WriteLine("Error!"); break;
}

26. Switch case statement
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switch (animal)
{
case "dog" :
Console.WriteLine("MAMMAL");
break;
case "crocodile" :
case "tortoise" :
case "snake" :
Console.WriteLine("REPTILE");
break;
default :
Console.WriteLine("There is no such animal!");
break;
}

27. Practice the programming
Practice is a habit.
Practice is a routine.
Practice does not need to remember.
Practice comes by practicing.
Practice needs dedication and commitment.
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NEVER hesitate to
contact should you
have any question
Dr.Atif Shahzad