Dart: Decision Making

# If Statement

if(boolean_expression){ 
   // statement(s) will execute if the boolean expression is true. 
} 

Example

void main() { 
   var  num=15; 
   if (num>0) { 
      print("number is positive"); 
   }    
}

=> output

number is positive 

# If Else Statement

if(boolean_expression){ 
   // statement(s) will execute if the Boolean expression is true. 
} else { 
   // statement(s) will execute if the Boolean expression is false. 
} 

Example

void main() { 
   var num = 21; 
   if (num % 2==0) { 
      print("Even"); 
   } else { 
      print("Odd"); 
   } 
}

=> output

Odd

# If Else Ladder

if (boolean_expression1) { 
   //statements if the expression1 evaluates to true 
} 
else if (boolean_expression2) { 
   //statements if the expression2 evaluates to true 
} 
else { 
   //statements if both expression1 and expression2 result to false 
} 

Example

void main() { 
   var num = 20; 
   if(num > 0) { 
      print("${num} is positive"); 
   } 
   else if(num < 0) { 
      print("${num} is negative"); 
   } else { 
      print("${num} is neither positive nor negative"); 
   } 
}  

=> output

20 is positive

# Switch Case Statement

switch(variable_expression) { 
   case constant_expr1: { 
      // statements; 
   } 
   break; 
  
   case constant_expr2: { 
      //statements; 
   } 
   break; 
      
   default: { 
      //statements;  
   }
   break; 
} 

Example

void main() { 
   var grade = "A"; 
   switch(grade) { 
      case "A": {  print("Excellent"); } 
      break; 
     
      case "B": {  print("Good"); } 
      break; 
     
      case "C": {  print("Fair"); } 
      break; 
     
      case "D": {  print("Poor"); } 
      break; 
     
      default: { print("Invalid choice"); } 
      break; 
   } 
}  

=> output

Excellent

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