Format anomoly

[JohnNichols]

    !  Known Errors
4373 Write(*,8126)NJL,NM1
    Write(12,8126)

8126 FORMAT("    STOP  as " :: ,2I10)

The double colon does not cause an error, I mistyped, it should be inside the " "

Is this standard Fortran, what does it do?  

This is from the McMaster Uni program, I am down to a few minor errors and this traps two of them. 

[Steve_Lionel]

Yes, it is standard conforming. Colon is a standard control edit descriptor that says to not process more of the format unless there are unused items in the I/O list. You have two of them, and the standard allows there to be no comma between them. I don't think it behaves any different than a single colon.

[jimdempseyatthecove]

Steve,

Can the FORTMAT have more than one : at different positions in the FORMAT statement? e.g.

    !  Known Errors
4373 Write(*,8126)NJL,NM1 ! two items
    Write(12,8126)NJL ! one item
    Write(1,8126) ! no items

8126 FORMAT("    STOP  as :" : ,I10 :, I10)

Jim Dempsey

[Steve_Lionel]

---

@jimdempseyatthecove wrote:

Steve,

Can the FORMAT have more than one : at different positions in the FORMAT statement?

---

Sure, no problem. But your example doesn't show the effect because the I10 would stop processing. The primary use of the colon edit descriptor is when you have non-data transferring descriptors you want to skip if there are no more items. The most common example of this is a comma-list.

program test
implicit none
integer :: a(5) = [1,2,3,4,5]
integer :: i

do i=1,5
  write (*,'(*(I2,:,","))') a(1:i)
  end do
end program test

D:\Projects>t.exe
 1
 1, 2
 1, 2, 3
 1, 2, 3, 4
 1, 2, 3, 4, 5

Without the colon, you'd see this:

 1,
 1, 2,
 1, 2, 3,
 1, 2, 3, 4,
 1, 2, 3, 4, 5,

[jimdempseyatthecove]

>>The double colon does not cause an error, I mistyped, it should be inside the " "

From your code snip, I think one of the :'s should have been inside the ""'s and the other outside the ""'s.

Jim Dempsey

[JohnNichols]

They are both inside the quotations.  I use it as simple device to line up numbers so it is quick to read. 

No idea why I use ::  always have, lost in the mists of time. 

This is from the McMaster Program, I have the code running, sorted out the last of the lost goto's, now to make sense of the thesis and the code, both are a little cryptic and the lack of a meaningful output is annoying.  

[jimdempseyatthecove]

Great example!

I've had many occasions to want to do just that.

Jim Dempsey