Scope of DO Variables

1. I is recalculated at the top of the loop and then compared with < expr2 >,
2. if the loop has finished, execution jumps to the statement after the corresponding END DO,
3. I retains the value that it had just been assigned.

For example,

    DO i = 4, 45, 17 
     PRINT*, "I in loop = ",i
    END DO
    PRINT*, "I after loop = ",i

will produce

    I in loop =  4
    I in loop =  21
    I in loop =  38
    I after loop =  55

An index variable may not have its value changed in a loop.

For more information, click here