Fortran Comments

Comments should be used liberally to improve readability. The following are the rules for making comments:

All characters following an exclamation mark, !, except in a character string, are commentary, and are ignored by the compiler.

PROGRAM  TestComment1
   ..........
   READ(*,*)  Year   ! read in the value of Year
   ..........
   Year = Year + 1   ! add 1 to Year
   ..........
END PROGRAM  TestComment1

An entire line may be a comment

! This is a comment line
!
PROGRAM  TestComment2
   .........
   ! This is a comment line in the middle of a program
   .........
END PROGRAM  TestComment2

A blank line is also interpreted as a comment line.

PROGRAM  TestComment3
   ..........
   READ(*,*)  Count

! The above blank line is a comment line
   WRITE(*,*)  Count + 2
END PROGRAM  TestComment3