鍍金池/ 教程/ Java/ Fortran關(guān)系運算符
Fortran還原功能
Fortran關(guān)系運算符
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Fortran關(guān)系運算符

下表列出了所有的Fortran支持的關(guān)系運算符。假設(shè)變量A=10和變量B=20，則：

操作符 等同 描述 示例
== .eq. 檢查兩個操作數(shù)的值相等與否，如果是，則條件變?yōu)檎妗?/td> (A == B) i不為 true.
/= .ne. 檢查，兩個操作數(shù)的值相等與否，如果值不相等，則條件變?yōu)檎妗?/td> (A != B) 為 true.
> .gt. 檢查，左操作數(shù)的值大于右操作數(shù)的值，如果是的話那么條件為真。 (A > B)不為true.
< .lt. 檢查，左操作數(shù)的值是否小于右操作數(shù)的值，如果是的話那么條件為真。 (A < B) 是 true.
>= .ge. 檢查，左邊的操作數(shù)的值是否大于或等于右操作數(shù)的值，如果是，則條件變?yōu)檎妗?/td> (A >= B) 不為 true.
<= .le. 檢查，左邊的操作數(shù)的值是否小于或等于右操作數(shù)的值，如果是，則條件變?yōu)檎妗?/td> (A <= B) 為 true.

示例

試試下面的例子就明白所有在Fortran語言可用的邏輯運算符：

program logicalOp

! this program checks logical operators
implicit none  

   ! variable declaration
   logical :: a, b
   
   ! assigning values 
   a = .true.   
   b = .false. 
   
   if (a .and. b) then
      print *, "Line 1 - Condition is true"
   else
      print *, "Line 1 - Condition is false"
   end if
   
   if (a .or. b) then
      print *, "Line 2 - Condition is true"
   else
      print *, "Line 2 - Condition is false"
   end if
          
   ! changing values 
   a = .false.   
   b = .true. 
   
   if (.not.(a .and. b)) then
      print *, "Line 3 - Condition is true"
   else
      print *, "Line 3 - Condition is false"
   end if
   
   if (b .neqv. a) then
      print *, "Line 4 - Condition is true"
   else
      print *, "Line 4 - Condition is false"
   end if
   
   if (b .eqv. a) then
      print *, "Line 5 - Condition is true"
   else
      print *, "Line 5 - Condition is false"
   end if
   
end program logicalOp

當(dāng)編譯并執(zhí)行上述程序,將產(chǎn)生以下結(jié)果：

Line 1 - Condition is false
Line 2 - Condition is true
Line 3 - Condition is true
Line 4 - Condition is true
Line 5 - Condition is false

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