Control Structures in Programming

Control Structures in Programming

• Control flow dictates the order of instruction execution in a program.
• Types of control include:
  • Sequential control: Executes instructions in the order they appear.
  • Selection control: Executes instructions based on conditions, such as if statements.
  • Iterative control: Repeats the execution of instructions, commonly implemented with loops.

Selection Control: If Statements in Python

• An if statement evaluates a Boolean expression:
  • Executes the code block if the expression is True.
  • Skips to subsequent statements if false.
• Syntax:

  if expression:
      statement(s)
  

• Indentation is crucial; all statements within a block must be equally indented.

If-Else Statement

• If-else allows for two-way decisions:
  • Executes the if block if the condition is true; otherwise, it executes the else block.
• Syntax:

  if test expression:
      Body of if
  else:
      Body of else
  

Nested If Statements

• Nested if statements allow placing an if block inside another if:
  • Useful for multiple checks.

If-Elif-Else Statement

• Extends the if-else structure for multiple conditions:
  • Checks additional conditions using elif.
• Syntax:

  if test expression:
      Body of if
  elif test expression:
      Body of elif
  else:
      Body of else
  

Importance of Indentation

• Consistent indentation is significant in Python:
  • Headers must be indented uniformly for proper block recognition.

Exercises

• A practical exercise involves finding the maximum of three numbers using if statements.

Multiple Choice Questions (MCQs)

• Understanding True/False statements about if constructs and indentation in Python is essential:
  • If statements can exist without an else or elif header.
  • Indentation rules: headers must be indented consistently within the same statement.
• The elif header allows for multi-way selection efficiently.