Fortran provides another form of loop for convenience, since iterating over a fixed set of values is so common. The basic structure is as follows:

do variable = start-value, end-value, stride
    body
enddo
        

The stride value is automatically added to the loop variable after the body is executed during each iteration. This loop is equivalent to the following:

variable = start-value
do while ( variable <= end-value )
    body
    variable = variable + stride
enddo
        

This loop combines the initialization, condition, and housekeeping into one line to make the code slightly shorter and easier to read. It does not allow arbitrary Boolean conditions: It only works for loops that go from a starting value to an ending value. Any or all of the values can be variables.

The stride is optional, and if omitted, defaults to 1, regardless of the start and end values.

integer :: angle

! Initialization, condition, and housekeeping
do angle = 0, 359
    ! Body
    print *, 'sine(',angle,') = ', sin(angle * PI / 180.0d0)
enddo
            

integer :: angle

! Initialization, condition, and housekeeping
do angle = 359, 0
    ! Body
    print *, 'sine(',angle,') = ', sin(angle * PI / 180.0d0)
enddo