Fortran 77 includes almost all of Fortran 66 as a subset. We describe the differences briefly in the Appendix. The most important additions are a character string data type, file-oriented input/output statements, and random access I/O. Also, the language has been cleaned up considerably.

      In addition to implementing the language specified in the new Standard, our compiler implements a few extensions described in this section. Most are useful additions to the language. The remainder are extensions to make it easier to communicate with C procedures or to permit compilation of old (1966 Standard) programs.

2.1.  Double Complex Data Type

2.2.  Internal Files

2.3.  Implicit Undefined statement

2.4.  Recursion

2.5.  Automatic Storage

2.6.  Source Input Format

2.7.  Include Statement

2.8.  Binary Initialization Constants

2.9.  Character Strings

2.10.  Hollerith

2.11.  Equivalence Statements

2.12.  One-Trip DO Loops

2.13.  Commas in Formatted Input

2.14.  Short Integers

2.15.  Additional Intrinsic Functions