Conditional statements are fundamental in programming as they allow you to make decisions based on certain conditions. In Delphi/Object Pascal, conditional statements help control the flow of the program by executing different code blocks based on specific conditions.

1. If-Then Statement: Executes a block of code if a specified condition is true.
2. If-Then-Else Statement: Executes one block of code if a condition is true and another block if the condition is false.
3. Case Statement: Selects one of many code blocks to execute based on the value of an expression.

The if-then statement is the simplest form of conditional statement. It evaluates a condition and executes a block of code if the condition is true.

• age is a variable of type Integer.
• The if statement checks if age is greater than or equal to 18.
• If the condition is true, it executes WriteLn('You are an adult.');.

The if-then-else statement provides an alternative block of code to execute if the condition is false.

• The if statement checks if age is greater than or equal to 18.
• If the condition is true, it executes WriteLn('You are an adult.');.
• If the condition is false, it executes WriteLn('You are a minor.');.

The case statement is used when you have multiple conditions to check. It is more readable and efficient than multiple if-then-else statements.

• The case statement checks the value of grade.
• It executes the corresponding WriteLn statement based on the value of grade.
• If grade does not match any of the specified values, it executes the else block.

Write a program that checks if a number is positive and prints "Positive number" if true.

Solution

Write a program that checks if a number is even or odd and prints the result.

Solution

Write a program that takes a day of the week (1-7) and prints the corresponding day name.

Solution

• Forgetting the else block: Ensure you handle both true and false conditions when using if-then-else.
• Using = instead of :=: Remember that = is for comparison, while := is for assignment.
• Not using begin and end for multiple statements: If you have multiple statements in an if or else block, enclose them in begin and end.

In this section, you learned about conditional statements in Delphi/Object Pascal, including if-then, if-then-else, and case statements. These constructs allow you to control the flow of your program based on different conditions. Practice the exercises to reinforce your understanding and prepare for more complex control structures in the next section.