递归函数运行，输入数据后，没报错但程序不动

xiejihong0306

彭国论教材EX0829.F90，用递归函数实现阶乘。


可我遇到了下面这个问题，按照粘贴的源代码那样，运行后输入n!，程序没报错，也没输出结果，想了半天实在没看懂哪有问题，


如果可以的话，想请高人解惑，万分感谢

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补充：  不好意思题干描述有点问题，我输入的9 ，没加感叹号

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01	! NOTE：P209

02	!  A sample code that reveals the principle of recursive functions and the calculation process

03	program ProgramName

04	implicit none

05	integer ExitKey

06

07	integer(kind=4) :: n

08	integer(kind=4), external :: fact

09	write(unit=6, fmt="('N = ')")

10	read (unit=5, fmt=*) n

11	write(unit=6, fmt="(I3,'! = ', I8)") n, fact(n)

12

13	! Avoid having the command window exit before the results are output

14	write ( *, *) 'Press input any words to exit...'

15	read ( *, *) ExitKey

16

stop

17	end program ProgramName

18

19

20	recursive integer(kind=4) function fact(n) result(ans)

21	implicit none

22	integer(kind=4), intent(in) :: n

23	integer(kind=4), save :: count = 1

24	integer(kind=4) :: localcount, temp

25	localcount = count

26	count = count + 1

27	write(unit=6, fmt="(I2, 'th enter, n = ', I2)") localcount, n

28	!  The IF-ELSE combination of multiple judgments only executes the first module that matches the condition

29	!  and then jumps to END IF to leave the statement.

30	if ( n < 0 ) then

31

ans = -1

32	write(unit=6, fmt="(I2, 'th exit, n = ', I2, 'ans = ', I8)") localcount, n, ans

33

return

34	else if ( n <=1 ) then

35

ans = 1

36	write(unit=6, fmt="(I2, 'th exit, n = ', I2, 'ans = ', I8)") localcount, n, ans

37

return

38

end if

39	temp = n - 1

40	ans = n * fact(temp)

41	write(unit=6, fmt="(I2, 'th exit, n = ', I2, 'ans = ', I8)") localcount, n, ans

42

return

43	end function fact

Transpose

gfortran的函数里面写输出会发生混乱,ifort应该没这个问题

[Fortran] 纯文本查看 复制代码

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1	integer(kind=4) :: n

2	integer(kind=4), external :: fact

3	integer::f

4	write(unit=6, fmt="('N = ')")

5	read (unit=5, fmt=*) n

6

f=fact(n)

7	write(unit=6, fmt="(I3,'! = ', I8)") n, f

     不要同时输出即可

布衣龙共

输入 3 就行了。不要输入 3!

此外，可能存在递归IO占用问题，详解：
http://recursiveio.w.fcode.cn/

xiejihong0306

布衣龙共 发表于 2022-10-8 11:25
输入 3 就行了。不要输入 3!

此外，可能存在递归IO占用问题，详解：

不好意思我题干描述有点问题，我输入的9 ，没加感叹号

xiejihong0306

Transpose 发表于 2022-10-8 11:17
gfortran的函数里面写输出会发生混乱,ifort应该没这个问题
[mw_shl_code=fortran,true]      integer(kind= ...

牛逼，分开写之后完美解决了，原来是gFortran输出混乱的问题，谢谢你！

--------------------------------

N =
5
1th enter, n =  5
2th enter, n =  4
3th enter, n =  3
4th enter, n =  2
5th enter, n =  1
5th exit, n =  1ans =        1
4th exit, n =  2ans =        2
3th exit, n =  3ans =        6
2th exit, n =  4ans =       24
1th exit, n =  5ans =      120
  5! =      120
Press input any words to exit...