PRINT Statement

This is the simplest form of directing unformatted data to the standard output channel, for example,

   PROGRAM Outie
    CHARACTER(LEN=*), PARAMETER :: long_name = &
              "Llanfairphwyll...gogogoch"
    REAL :: x, y, z
    LOGICAL :: lacigol
    x = 1; y = 2; z = 3
    lacigol = (y .eq. x)
    PRINT*, long_name
    PRINT*, "Spock says ""illogical&
            &Captain"" "
    PRINT*, "X = ",x," Y = ",y," Z = ",z
    PRINT*, "Logical val: ",lacigol
   END PROGRAM Outie

produces on the screen,

    Llanfairphwyll...gogogoch
    Spock says "illogical Captain"
    X =    1.000  Y =    2.000  Z =    3.000
    Logical val:  F

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As can be seen from the above example, the PRINT statement takes a comma separated list of things to print, the list can be any printable object including user-defined types (as long as they don't contain pointers). The * indicates the output is in free (default) format. Fortran 90 supports a great wealth of output (and input) formatting which is not all described here!

There are a couple of points to raise,

• LOGICAL variables can be printed,

      lacigol = (y .eq. x)

  generates an F signifying .FALSE..

• Strings can be split across lines,

      PRINT*, "Spock says ""illogical&
              &Captain"" "

  If a CHARACTER string crosses a line indentation can still be used if an & is appended to the end of the first line and the position from where the string is wanted to begin on the second - see the Spock line in the example; the & s act like a single space.

• The double " in the string, the first one escapes the second. Strings may be delimited by the double or single quote symbols, " and ', but these may not be mixed in order to delimit a string. The following would produce the same output as the statement in the program,

      PRINT*, 'Spock says "illogical&
              &Captain" '

  In this case the (unsued ") delimiter does not have to be escaped.

• Notice how the output has many more spaces than the PRINT statement indicates. This is because output is unformatted. The default formatting is likely to be different between compilers.
• Each PRINT statement begins a new line, non-advancing I/O is available but we have to specify it in a FORMAT statement.

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