fortran中的运行时错误

Question

我是FORTRAN的初学者。 最近，我尝试设计一个简单的程序来计算排列和组合。 它将具有一个“菜单”，供用户选择进行操作的选项。

      !/*-------MAIN PROGRAM STARTS-------*/
      !PURPOSE: TO CALCULATE COMBINATIONS AND PERMUTATIONS
      PROGRAM COMBINATION_PERMUTATION
      IMPLICIT NONE

      !DECLARATION OF VARIABLES
      REAL N, K, FACT, COMBINATION, PERMUTATION
      INTEGER CHOICE

      !CHOICE MENU
      CALL MENU

      !USER INPUT OF CHOICE
      READ(*,*) CHOICE

      !EXECUTION OF CODE BASED ON USER'S CHOICE
      SELECT CASE(CHOICE)
        CASE(1)
            !CALLS SUBROUTINE FOR COMBINATION 
            CALL COMBINATION_CALC (N, K, FACT, COMBINATION)            
        CASE(2)
            !CALLS SUBROUTINE FOR PERMUTATION
            CALL PERMUTATION_CALC (N, K, FACT, PERMUTATION)
        CASE(3)
            !EXITS THE PROGRAM
            STOP 
        CASE DEFAULT
        !INVALID CHOICE LEADS TO MENU BACK
        WRITE(*,*) 'INVALID CHOICE! PLEASE CHOOSE AN OPTION TO CONTINUE'
        CALL MENU
      END SELECT

      END PROGRAM COMBINATION_PERMUTATION
      !/*-------MAIN PROGRAM ENDS-------*/


      !/*-------SUB PROGRAMS START-------*/
      !FUNCTION FOR FACTORIAL
      FUNCTION FACT(N)
      IMPLICIT NONE
      REAL FACT, N
      INTEGER P, I
      P=1
      DO I=1, N
        P=P*I
      END DO
      FACT=P
      RETURN
      END FUNCTION 

      !SUBROUTINE FOR MENU
      SUBROUTINE MENU
      IMPLICIT NONE
      WRITE(*,*) ' CHOOSE AN OPTION TO CONTINUE.. '
      WRITE(*,*) ' 1. COMBINATION '
      WRITE(*,*) ' 2. PERMUTATION '
      WRITE(*,*) ' 3. EXIT PROGRAM '
      RETURN
      END SUBROUTINE MENU

      !SUBROUTINE FOR COMBINATION
      SUBROUTINE COMBINATION_CALC (N, K, FACT, COMBINATION)
      IMPLICIT NONE

      REAL N, K, FACT, COMBINATION

      WRITE(*,*) ' WHAT IS THE VALUE OF N? '
      READ(*,*) N

2     WRITE(*,*) ' WHAT IS THE VALUE OF K? '
      READ(*,*) K

      IF (K<0) THEN 
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE MORE THAN 0! '
            GO TO 2
        ELSE IF (K>N)THEN
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE LESS THAN N! '
            GO TO 2
        ELSE
      END IF 

      COMBINATION=FACT(N)/(FACT(N-K)*FACT(N))
      WRITE(*,*) ' HENCE, THERE ARE ', COMBINATION, ' WAYS TO ARRANGE. '
      CALL MENU
      RETURN
      END SUBROUTINE COMBINATION_CALC

      !SUBROUTINE FOR PERMUTATION
      SUBROUTINE PERMUTATION_CALC (N, K, FACT, PERMUTATION)
      IMPLICIT NONE

      REAL N, K, FACT, PERMUTATION

      WRITE(*,*) ' WHAT IS THE VALUE OF N? '
      READ(*,*) N

3     WRITE(*,*) ' WHAT IS THE VALUE OF K? '
      READ(*,*) K

      IF (K<0) THEN 
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE MORE THAN 0! '
            GO TO 3
        ELSE IF (K>N) THEN
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE LESS THAN N! '
            GO TO 3
        ELSE
      END IF

      PERMUTATION=FACT(N)/FACT(N-K)
      WRITE(*,*) ' HENCE THERE ARE', PERMUTATION,' WAYS TO ARRANGE. '
      CALL MENU      
      RETURN
      END SUBROUTINE PERMUTATION_CALC
      !/*-------SUB PROGRAMS END-------*/

每当我输入输入1或2选择要进行的案件时，我都会遇到运行时错误。

该错误在弹出窗口中显示如下：

---

运行时间错误

当需要过程时，尝试将参数编号为3的例程称为real（kind = 1）。

COMBINATION_CALC-输入文件的组合置换。用于第62行[+0068] main-输入文件的组合置换。用于23行[+ 00e2]

---

据我所知，COMBINATION_CALC中的第三个参数是“ FACT”，用于计算阶乘。 我无法理解该错误。 请指导我。 提前致谢..

---

更新

我已经使用yosukesabai给出的修复程序修复了运行时错误...我的程序现已完成..但是，整数溢出对我来说是个新问题。 我将REAL声明更改为INTEGER（KIND = 4）。.当N值和K值大于12时，组合和置换的结果答案将很大...我可以知道如何解决此问题吗？

这是我的程序的新代码...

          !/*-------MAIN PROGRAM STARTS-------*/
      !PURPOSE: TO CALCULATE COMBINATIONS AND PERMUTATIONS
      !CREATED BY: RETHNARAJ RAMBABU
      !DATE: 28/10/2011
      PROGRAM COMBINATION_PERMUTATION
      IMPLICIT NONE

      !DECLARATION OF VARIABLES
      INTEGER CHOICE, N, K
      INTEGER(KIND=4) COMBINATION, PERMUTATION
      INTEGER, external :: FACT

      !CHOICE MENU
1     WRITE(*,*) ' CHOOSE AN OPTION TO CONTINUE.. '
      WRITE(*,*) ' 1. COMBINATION '
      WRITE(*,*) ' 2. PERMUTATION '
      WRITE(*,*) ' 3. EXIT PROGRAM '

      !USER INPUT OF CHOICE
      READ(*,*) CHOICE

      !EXECUTION OF CODE BASED ON USER'S CHOICE
      SELECT CASE(CHOICE)
        CASE(1)
            !CALLS SUBROUTINE FOR COMBINATION 
            CALL COMBINATION_CALC (N, K, FACT, COMBINATION)  
            GO TO 1          
        CASE(2)
            !CALLS SUBROUTINE FOR PERMUTATION
            CALL PERMUTATION_CALC (N, K, FACT, PERMUTATION)
            GO TO 1
        CASE(3)
            !EXITS THE PROGRAM
            STOP 
        CASE DEFAULT
        !INVALID CHOICE LEADS TO MENU BACK
        WRITE(*,*) 'INVALID CHOICE! PLEASE CHOOSE AN OPTION TO CONTINUE'
        GO TO 1
      END SELECT

      END PROGRAM COMBINATION_PERMUTATION
      !/*-------MAIN PROGRAM ENDS-------*/


      !/*-------SUB PROGRAMS START-------*/
      !FUNCTION FOR FACTORIAL
      FUNCTION FACT(N)
      IMPLICIT NONE
      INTEGER N, P, I, FACT
      P=1
      DO I=1, N
        P=P*I
      END DO
      FACT=P
      RETURN
      END FUNCTION 

      !SUBROUTINE FOR COMBINATION
      SUBROUTINE COMBINATION_CALC (N, K, FACT, COMBINATION)
      IMPLICIT NONE

      INTEGER N, K, FACT
      INTEGER(KIND=4) COMBINATION

      WRITE(*,*) ' WHAT IS THE VALUE OF N? '
      READ(*,*) N

2     WRITE(*,*) ' WHAT IS THE VALUE OF K? '
      READ(*,*) K

      IF (K<0) THEN 
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE MORE THAN 0! '
            GO TO 2
        ELSE IF (K>N)THEN
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE LESS THAN N! '
            GO TO 2
        ELSE
      END IF 

      COMBINATION=FACT(N)/(FACT(N-K)*FACT(K))
      WRITE(*,*) ' HENCE, THERE ARE ', COMBINATION, ' WAYS TO ARRANGE. '
      RETURN
      END SUBROUTINE COMBINATION_CALC

      !SUBROUTINE FOR PERMUTATION
      SUBROUTINE PERMUTATION_CALC (N, K, FACT, PERMUTATION)
      IMPLICIT NONE

      INTEGER N, K, FACT
      INTEGER(KIND=4)PERMUTATION

      WRITE(*,*) ' WHAT IS THE VALUE OF N? '
      READ(*,*) N

3     WRITE(*,*) ' WHAT IS THE VALUE OF K? '
      READ(*,*) K

      IF (K<0) THEN 
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE MORE THAN 0! '
            GO TO 3
        ELSE IF (K>N) THEN
            WRITE(*,*) ' ERROR! VALUE OF K SHOULD BE LESS THAN N! '
            GO TO 3
        ELSE
      END IF

      PERMUTATION=FACT(N)/FACT(N-K)
      WRITE(*,*) ' HENCE THERE ARE', PERMUTATION,' WAYS TO ARRANGE. '
      RETURN
      END SUBROUTINE PERMUTATION_CALC
      !/*-------SUB PROGRAMS END-------*/

Answer 1

在代码顶部附近，

  PROGRAM COMBINATION_PERMUTATION
  IMPLICIT NONE

  !DECLARATION OF VARIABLES
  REAL N, K, FACT, COMBINATION, PERMUTATION
  INTEGER CHOICE

在这里，您说FACT是实数，因此fortran假定它是实数。 但是，您的意思是这是对您在同一文件中定义的功能的引用。 所以像这样修改

  !DECLARATION OF VARIABLES
  REAL N, K, COMBINATION, PERMUTATION
  INTEGER CHOICE
  REAL, external :: FACT

external是fortran的说法，它是您在程序块之外的某个位置（程序，子例程或函数）定义的函数

---

（如果您不在乎，请在此处忽略下面的内容）

我注意到没有传递函数引用的意义。 因此，您可能想停止传递函数，而只从子例程combination_calc调用该函数。 在这种情况下，n，k，combination是该子例程的三个参数，在combination_calc内部，您将获得real, external :: fact 。

Answer 2

关于INTEGER溢出，将变量P（在FACT函数内）声明为REAL而不是INTEGER。 INTEGER（4）变量不能超过2^31和12! < 2^31 < 13! 12! < 2^31 < 13!

但是请注意：REAL值也可能发生溢出（在我的计算机上为35! ： 34!=2.9523282E+38 ）。 使用双精度（REAL（8））时，溢出发生在171! （ 170! = 7.2574156153+306 ）