Programming Basics: Variables and Control Structures

Variables and Data Types

• Variables store information in a program.
• Variables are like containers that hold data.
• Data types define the kind of information a variable can hold.
• Common data types:
  • Integer: Represents whole numbers.
  • Float: Represents numbers with decimals.
  • String: Represents text or characters.
  • Boolean: Represents True or False values.
  • Creating a variable involves giving it a name and assigning a value, for example: age = 25.
  • The = sign is used to assign a value to a variable.
  • Variables can be changed after they are created, for example: age = 26.
  • Variables can be used in calculations or to display information.
  • Example: print("Your age is:", age).

Control Structures

• Control structures guide the flow of a program.
• Conditional statements allow a program to choose different paths based on conditions.
  • The most common conditional statement is the if statement.
  • Example:

    if age >= 18:
        print("You are an adult.")
    else:
        print("You are a minor.")
    

• Loops allow a program to repeat actions multiple times.
  • For loops are used when the number of iterations is known beforehand.
    • Example:

      for i in range(5):
          print("This is loop iteration number", i)
      

  • While loops are more flexible and used when the number of iterations is unknown.
    • Example:

      count = 0
      while count < 5:
          print("Count is:", count)
          count += 1
      

Other Key Concepts

• Syntax refers to the rules governing how code must be written in a programming language.
• Iteration is the process of repeating a set of instructions multiple times, usually using loops.

Variables and Data Types

• Variables are like containers to store information in code.
• Variables are assigned a name and a value.
• You can change the value of a variable at any time.
• Variables are used to store and manipulate information in programs.
• Data types tell us what kind of data is being stored.
• Common data types:
  • Integer: Whole numbers (e.g., 5, -3).
  • Float: Numbers with decimal points (e.g., 3.14, 0.5).
  • String: Text or characters, enclosed in double quotation marks (e.g., "Hello", "Coding is fun!").
  • Boolean: True or False values (e.g., True, False).

Control Structures

• Control structures guide the flow of execution in programs.
• Conditional statements let the program choose different paths based on conditions.
• The if statement is a common conditional statement.
• Example if statement:

  age = 18
  if age >= 18:
      print("You are an adult.")
  else:
      print("You are a minor.")
  

• How if statements work:
  • If the condition (age >= 18 in this case) is true, the block of code inside the if statement executes.
  • If the condition is false, the block of code inside the else statement executes (if there is an else block).

Loops

• Loops allow you to repeat a block of code multiple times without writing it out repeatedly.
• For loops are suitable when the number of iterations is known beforehand.
  • Structure of a for loop:
    • Initialization: Sets up the loop counter variable.
    • Condition: Determines when the loop stops.
    • Incrementing: Changes the loop counter variable with each iteration.
  • Example for loop:

    for i in range(5):
        print("This is loop iteration number", i)
    

  • This loop iterates five times (from 0 to 4), printing the current iteration number.
• While loops are more flexible, suited when the number of iterations is uncertain.
  • Structure of a while loop:
    • The loop continues as long as the specified condition is true.
  • Example while loop:

    count = 0
    while count < 5:
        print("Count is:", count)
        count += 1 
    

  • This loop continues until the count variable reaches 5.

Glossary

• Syntax: The set of rules for writing code in a programming language.
• Iteration: Repeating a set of instructions or actions multiple times.

Variables and Data Types

• Variables: Store information that can be changed, similar to a box containing data.
• Creating a Variable: Assign a name and value to a variable, such as age = 25.
• Changing a Variable: Update the variable's value, for instance, age = 26 to reflect a change.
• Data Types: Specify the kind of data a variable holds, such as:
  • Integer: Whole numbers (e.g., 5, -3).
  • Float: Numbers with decimals (e.g., 3.14, 0.5).
  • String: Text or characters enclosed in double quotes (e.g., "Hello", "Coding is fun!").
  • Boolean: Represents truth values, True or False.

Control Flow Structures

• Control Structures: Determine the order of execution in a program.
• Conditional Statements (if statements): Allow the program to make decisions based on whether a condition is true or false.
  • Example: if age >= 18: print("You are an adult") else: print("You are a minor").
• Loops: Repeat a block of code multiple times.
  • for loops: Useful when the number of iterations is known beforehand.
    • Example: for i in range(5): print("This is loop iteration number", i).
  • while loops: Execute code repeatedly as long as a condition remains true.
    • Example: count = 0; while count < 5: print("Count is:", count); count += 1.

Programming Concepts

• Syntax: Rules that define how code must be written in a particular programming language.
• Iteration: Repeating a set of instructions using loops, such as for or while.