Conditional Statements

Conditional statement structures require the programmer to specify one or more conditions that will be evaluated or tested by the program, one or more statements to be executed if the condition is determined to be true, and optionally, other statements to be executed if the condition is determined to be false.

Statement	Description
if - then statement	An if - then statement consists of a boolean expression followed by one or more statements.
If then-else statement	An if - then statement can be followed by an optional else statement, which executes when the boolean expression is false.
If then-else if statement	It is a structure used to sequentially check multiple conditions.
nested if statements	You can use one if or else if statement inside another if or else if statement(s).
case statement	A case statement allows a variable to be tested for equality against a list of values.
case - else statement	It is similar to the if-then-else statement. Here, an else term follows the case statement.

if-else statement example

var
 I:Integer;
{
 I =3;
 if (I <> 0)
 {
   ShowMessage('The number is not equal to the number 0.');
 }
}

If-then-else statement example

var
  age: Integer;
{
  age = 28;

  if (age >= 18)
    ShowMessage('You are an adult.')
  else
    ShowMessage('You are a minor.');
}

If then-else if statements example

var
  score: Integer;
{
  score = 85;

  if (score >= 90) 
    ShowMessage('Grade: A')
  else if (score >= 80)
    ShowMessage('Grade: B')
  else if (score >= 70)
    ShowMessage('Grade: C')
  else if (score >= 60)
    ShowMessage('Grade: D')
  else
    ShowMessage('Grade: F');
}

nested if statements example

var
  age: Integer;
  hasPermission: Boolean;
{
  age = 20;
  hasPermission = True;

  if (age >= 18)
  {
    if (hasPermission)
      ShowMessage('Access granted.')
    else
      ShowMessage('Access denied. Permission required.');
  }
  else
    ShowMessage('You are a minor. Access denied.');
}

case statement example

var
  grade: char;
{
  grade = 'F';
  
  case grade of
  {
    'A': ShowMessage('Excellent!');
    'B': ShowMessage('Good job!');
    'C': ShowMessage('Fair!');
    'D': ShowMessage('Needs improvement!');
    'F': ShowMessage('Failed!');
  }
}

case - else statement example

var
  day: integer;
{
  day = 10;
  
  case day of
  {
    1: ShowMessage('Monday');
    2: ShowMessage('Tuesday');
    3: ShowMessage('Wednesday');
    4: ShowMessage('Thursday');
    5: ShowMessage('Friday');
    6: ShowMessage('Saturday');
    7: ShowMessage('Sunday');
  else
    ShowMessage('Invalid day!');
  }
}