input - 将不正确的值读入变量的尝试会更改其值吗？

Question

如果存在iostat关键字，则在发生I/O错误时程序不会停止。然后，如果我尝试将不正确的值读取到标量变量i中，该变量会保持不变吗？以下似乎有效:

program test
   integer :: i, stat

   i = 1

   do
      write (*, "('i = ')", advance='no')
      read (*, *, iostat=stat) i

      if (stat .eq. 0) then
         write (*, "('Valid integer. i has been set to ', I0)") i
      else
         write (*, "('Bad integer. i is still ', I0)") i
      end if
   end do
end program test

我可以依靠Fortran 2003中的这种行为吗？

Answer 1

否，读取失败后变量的值是不确定的。

Fortran 2008，9.11.2

If an error condition occurs during execution of an input/output statement that contains either an ERR= specifier or an IOSTAT= specifier then:

...

if the statement is a READ statement or the error condition occurs in a wait operation for a transfer initiated by a READ statement, all input items or namelist group objects in the statement that initiated the transfer become undefined;