可以使用一個 if 或else if 在另一個if或else if語句中。

語法

嵌套if語句的語法如下：

if ( logical_expression 1) then
   !Executes when the boolean expression 1 is true 
   …
   if(logical_expression 2)then 
   ! Executes when the boolean expression 2 is true 
   …
   end if
end if

例子

program nestedIfProg
implicit none
   ! local variable declaration
   integer :: a = 100, b= 200
 
   ! check the logical condition using if statement
   if( a == 100 ) then
  
   ! if condition is true then check the following 
      
   if( b == 200 ) then
  
   ! if inner if condition is true 
   print*, "Value of a is 100 and b is 200" 
  
   end if
   end if
   
   print*, "exact value of a is ", a
   print*, "exact value of b is ", b
 
end program nestedIfProg

當上述代碼被編譯和執行時，它產生了以下結果：

Value of a is 100 and b is 200
exact value of a is 100
exact value of b is 200