F# - if else

if conditional statements are used to execute code blocks based on a conditional expression. F# provides the following conditional statements

It provides the following features

• simple if statements
• if else statements
• if else if else
• nested if else

F# conditional statements are expressions that return boolean type - true and false.

F# uses spaces to indent inside code blocks to have scopes instead of {}.

F# if conditional statement

F# if the conditional statement is used to execute code block based on conditional expression statements.

The conditional expression contains either single or multiple conditions.

if the conditional expression is always evaluated as true or false. if it is true, It executes a code block.

Syntax

if condition
    //code block

Here is an example

if condition {
    //code block
    }

condition is a Boolean expression that returns true or false

• if the condition is true, the code block is executed.
• if the condition is false, the code block is not executed. Here is an example of f# if conditional true example

let number: int32=20;

if number%2=0 then
   printfn "%d is an Even Number " number

Output:

20 is an Even Number

Here is a simple if conditional statement false example

let number: int32=21;

if number%2<>0 then
   printfn "%d is an Odd Number " number

Output:

21 is an Odd Number

F# if else conditional statements

if else in f# is used to execute code blocks based on true and false conditional expressions.

Syntax:

if condition then
       //code block based on true conditional value
else
       // code block based on false conditional value

condition is a Boolean expression that returns true or false

• if the condition is true, code block inside if block is executed.
• if the condition is false, the code block inside the else block is executed. Here is an example of f# if conditional true example

Here is a java if else conditional expression example

let number: int32=25;

if number%2=0 then
   printfn "%d is an Even Number " number
else
   printfn "%d is an Odd Number " number

Output:

25 is an Odd Number

F# if then elif else statement example

This is a combination of if and elif and if statements.

This is used to execute code blocks based on multiple conditions.

Syntax:

if condition1 then
    //code block executes based on the condition1 is true

elif condition2 then
    //code block executes based on the condition2 is true

else
    //code block executes based on the condition1 is false

Here is an example

let number: int32=21;

if number < 9 then
   printfn "%d is a Single Digit Number " number

elif (number > 9) && (number<99) then
   printfn "%d is a Two-Digit Number " number

elif (number > 99) && (number<999) then
   printfn "%d is a Three-Digit Number " number

else
   printfn "%d is a Four-Digit Number " number

Output:

2 is a Two-Digit Number

Nested If F# examples

if statements are nested inside another if or else or elif statements as given below

let number: int32=2;

if number < 9 then
   printfn "%d is a Single Digit Number " number
   if number%2=0 then
      printfn "%d is an Event Number " number
    else
      printfn "%d is an Odd Number " number

elif (number > 9) && (number<99) then
   printfn "%d is a Two-Digit Number " number

elif (number > 99) && (number<999) then
   printfn "%d is a Three-Digit Number " number

else
   printfn "%d is a Four Digit Number " number

Output

2 is a Single Digit Number
2 is an Event Number