尝试将不正确的值读入变量会改变它的值吗？

Question

如果存在 iostat 关键字，则程序不会在出现 I/O 错误时停止。然后，如果我尝试将不正确的值读入标量变量，i 说，这个变量会保持不变吗？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

我可以依赖 Fortran 2003 中的这种行为吗？

Answer 1

不是，读取失败后变量的值未定义。

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;

尝试将不正确的值读入变量会改变它的值吗？

Will the attempt to read an improper value into a variable change its value?

error-handling

fortran

input

fortran2003