This tutorial introduces you to the ancient world of FORTRAN (only joking ... FORTRAN is alive and well as testified by the FORTRAN 2008). This is not a particularly useful language for developing Windows applications, but has a firm footing in the world of mathematics from whence it originated back in 1954.
The skeleton for a FORTRAN program consists of just three lines, so it is quite compact.
PROGRAM name IMPLICIT NONE END PROGRAM name
Basic Data Types
FORTRAN supports integers, reals, logical and character data types. Examples of this would be:
INTEGER :: Counter REAL :: Value LOGICAL :: Boolean CHARACTER :: A, B CHARACTER*20 :: String
In the Fibonacci example below, there are four integers defined, FIRST, SECOND, TEMP and IX.
The DO Loop
The DO loop is equivalent to the for loop in C/C++. it's format is DO index = initial, maximum, step ... END DO. So, in the example below, we have DO IX = 1, 45, 1 which states execute the statements between the DO and END DO setting IX to an initial value of 1, ending the loop when IX reaches 45, and increment IX by one for every loop iteration.
Output To The Display
In the example below, lines 6, 7 and 12 output values to the console display. The format is WRITE (*,*) followed by one or more data fields to write.
This code has been compiled and tested using the gfortran front-end to the gcc compiler under Linux.
PROGRAM Fibonacci IMPLICIT NONE INTEGER :: FIRST, SECOND, TEMP, IX FIRST = 0 SECOND = 1 WRITE (*,*) FIRST WRITE (*,*) SECOND DO IX = 1, 45, 1 TEMP = FIRST + SECOND FIRST = SECOND SECOND = TEMP WRITE (*,*) TEMP END DO END PROGRAM Fibonacci