- Fortran is the
first high level
programming language
- There are multiple versions
of the
Fortran language
- Present day Fortran compiler
can translate:
- Fortran 77 (old style)
- Fortran 90/95 (new style)
- The old standard is
Fortran 77
- Uses fixed source form
- The established standard is
Fortran 90/95
(Fortran 95 has only minor changes to
Fortran 90)
- Uses Free source form
- The current standard (Fortran 2003) is being
implemented
- A new standard (Fortran 2008) is being
developed
- F90/F95 widely available
- F90/F95 will also compile F77 syntax
- Some F2003 features are available.
- A
program unit
is a
unit of compilation
- A
unit of compilation
can be one of:
- A Program unit
- A Subprogram (subroutine/function) unit
- A Module unit
- A Program unit
- Structure of a Fortran program:
program ProgramName ... (Program body) ... [stop] end [program ProgramName]
- Structure of a Procedure in Fortran:
subroutine SubroutineName(parameters) ... (Subroutine body) ... return end [subroutine]
- Structure of a Function in Fortran:
function FunctionName(parameters) ... (Function body) ... return(...) end [function]
- Structure of a Module in Fortran:
module ModuleName definition of variables CONTAINS definition of function end [module]The module was inspired by C++'s classes
- To print a string or variable to terminal:
print *, "Hello" print *, var
- To read a value from terminal:
read *, var
- Fortran program file:
- Filename's extension ends with .f :
assumed to be
Fortran 77 (old style) source
- Filename's extension ends with .f90 : assumed to be Fortran 90/95 (new style) source
- Filename's extension ends with .f :
assumed to be
Fortran 77 (old style) source
- How to compile a Fortran program:
f90 [ options ] prog.f f90 [ options ] prog.f90
- Example:
program Hello print *,"Hello World !"; end program Hello - Example Program:
(Demo above code)
- Prog file: click here
Compile with:
f90 Hello.f90
- Comments may be placed anywhere on the source line,
following a `!' character.
Example:
program Hello print *,"Hello World !"; ! This is a comment end program Hello
- A new line
will
end a statement
Example:
program Hello print *,"Hello World !" ! One statment print *,"Hello Again !" ! Another statment end program Hello
- Example Program:
(Demo above code)
- Prog file: click here
- You cannot break a statement
in to
multiple lines
(without telling the compiler)
Example:
program Hello print *, "Hello World !" end program HelloYou will get compile errors !!!
- Example Program:
(Demo above code)
- Prog file: click here
- To break a statement
in to
multiple lines , use the
continuation character &
Example:
program Hello print *, & "Hello World !" end program Hello
- Multiple statement on
one line
must be separated
by
a semi-colon (;)
Example:
print *,"H"; print *,"E";
- F90 has stolen many features from
C/C++
- One of the feature is
file inclusion
Example:
include 'filename.f90'That's the same as #include "filename.f90" in C/C++
-
SPACES has no meaning in Fortran 77
Example:
INTEGER i1 INTEGER i 1 IN TEGER i 1
All will define a variable "i1" in F77...
- Try to read this program:
integer i 1 in tegeri2 i 1=1 2 3 4 print *, "i1 = ", i1 i 2 = 23 45 print *, "i2 = ", i2
- Example Program:
(Demo above code)
- Prog file: click here
- Luckily, but spaces in F90 are meaningful !!
- Fortran is
case insensitive
- You will see me use lower case and upper case key words and variables all over the place :-)