Fortran - 嵌套 If 构造

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  简述

  你可以使用一个 if 或者 else if 另一个里面的声明 if 或者 else if 声明。
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  句法

  嵌套的语法if声明如下 -

  
  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
  

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  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
  

  编译并执行上述代码时，会产生以下结果 -

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