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

Question

If the iostat keyword is present, a program does not stop if an I/O error occurs. Then, if I try to read an improper value into a scalar variable, i sa

Answer 1

No, the value of the variable after an unsuccessful read is undefined.

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;