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• Selection statements


  Used to execute particular statements whether the value of the given condition evaluates to true or false
• Selection structures in C#

  • if and if...else statements
  • switch statement
• if-else statement


  1. Evaluate expression

  2. Execute statements if true

  3. Execute statements if false
• if-else-if statement


  1. Evaluate first if condition

  2. If true, execute statements and skip other conditions

  3. If false, evaluate next else if condition

  4. If none true, execute else statements
• switch statement


  Executes a block of statements based on the variable to be tested for equality against a list of values
• The variable or expression in the switch statement can only be an integer, a floating-point number, a character, or a string type</b>
• Each case label must contain a break statement to stop the flow control of the switch statement
• The switch statement may or may not contain a default statement, which must appear at the end of switch statement
• Conditional (ternary) operator


  A special type of decision-making operator used to perform an operation that evaluates a logical expression then selects between two single statements depending on whether the defined expression evaluates to true or false
• Ternary operator usage


  • int sum = 4 > 2 ? 4 + 2 : 4 - 2
  • int exam_score = 75; string result = exam_score >= 60 ? "Student passed the exam." : "Student failed the exam."
• The ternary operator is used as an alternative to if...else statements that contains a single statement body
• If statement


  A selection statement that executes a block of code if the condition is true.
• If-else statement


  A selection statement that executes one block of code if the condition is true, and another block of code if the condition is false.
• If-elif-else statement


  A selection statement that allows for multiple conditions to be evaluated and executed accordingly.
• False


  A value that represents the condition not being satisfied.
• True


  A value that represents the condition being satisfied.
• Loop


  A construct that enables a program to execute a block of statements or a loop body repetitively as long as the defined condition evaluates to true
• Looping structures in C#

  • while
  • do...while
  • for
• while loop


  1. Evaluate condition

  2. Execute loop body

  3. Reevaluate condition
• while loop


  • Repeats a block of statements as long as a given condition is true
  • Evaluates the condition first before executing the loop body
• do...while loop


  1. Execute loop body

  2. Evaluate condition
• do...while loop


  • Executes the loop body first before evaluating the given loop condition
  • Continues to execute the loop body until the condition evaluates to false
• for loop


  1. Initialization

  2. Condition evaluation

  3. Update condition

  4. Execute loop body
• for loop


  • Executes a block of statements for a specific number of times
  • Specifies the elements of counter-controlled-repetition in a single line
• break statement


  Terminates a loop or a switch statement and transfers the flow of program execution to the statements following the enclosing loop or switch statement
• continue statement


  Skips the remaining statements in the loop body and immediately reevaluates the condition if it's a while or do...while loop, or it jumps to the update step if it's a for loop
• String


  A sequential collection of characters that is used to represent text
• String variable initialization


  • Directly assigning a string literal
  • Using the new keyword and calling the String class constructor
• String variable initialization


  • string word = "Computer";
  • string strGreet = new string(word);
• String class properties


  • char - Gets the character at a specified index position
  • Length - Gets the total number of characters in the string
• String class methods


  • Contains(string value)
  • Equals(string value, StringComparison comparisonType)
  • IndexOf(char value)
  • Replace(char oldValue, char newValue)
  • ToString()
  • ToLower()
  • ToUpper()
• Strings are immutable
• StringBuilder class


  Represents a mutable string of characters that allows the user to expand the number of characters in the string object without allocating additional memory space
• Creating a StringBuilder object

  • StringBuilder strComputer = new StringBuilder("Computer");
  • strComputer.Append(" is a great invention.");
• StringBuilder class properties


  • char - Gets and sets the character at the specified index
  • Length - Gets the length of the current StringBuilder object
• StringBuilder class methods


  • Append(string value)
  • Equals(string value)
  • Clear()
  • Replace(char oldValue, char newValue)
  • ToString()
• Array


  A set of fixed number of values called elements that can be accessed using integer index. Elements on an array are of the same data type. Indices in an array starts at 0.
• Array


  • Used to store multiple values of the same data type at a time without declaring a different variable name for each value
  • Array elements can be of any data type
• Defining a one-dimensional array

  1. Declare a variable that refers to an array

  2. Create an instance of the array through the new operator
• One-dimensional array


  • int[] numbers = new int[10]
  • double[] grades = { 2.50, 2.75, 1.25, 5.0, 1.50 }