ANSI FORTRAN 77 Standard

X3.9 - 1978

Table of Contents

• 1 INTRODUCTION
  • 1.1 Purpose
  • 1.2 Processor
  • 1.3 Scope
    • 1.3.1 Inclusions.
    • 1.3.2 Exclusions.
  • 1.4 Conformance
    • 1.4.1 Subset Conformance.
  • 1.5 Notation Used in This Standard
  • 1.6 Subset Text
• 2 FORTRAN TERMS AND CONCEPTS
  • 2.1 Sequence
  • 2.2 Syntactic Items
  • 2.3 Statements, Comments, and Lines
    • 2.3.1 Classes of Statements.
  • 2.4 Program Units and Procedures
    • 2.4.1 Procedures.
    • 2.4.2 Executable Program.
  • 2.5 Variable
  • 2.6 Array
    • 2.6.1 Array Elements.
  • 2.7 Substring
  • 2.8 Dummy Argument
  • 2.9 Scope of Symbolic Names and Statement Labels
  • 2.10 List
  • 2.11 Definition Status
  • 2.12 Reference
  • 2.13 Storage
  • 2.14 Association
• 3 CHARACTERS, LINES, AND EXECUTION SEQUENCE
  • 3.1 FORTRAN Character Set
    • 3.1.1 Letters.
    • 3.1.2 Digits.
    • 3.1.3 Alphanumeric Characters.
    • 3.1.4 Special Characters.
    • 3.1.5 Collating Sequence and Graphics.
    • 3.1.6 Blank Character.
  • 3.2 Lines
    • 3.2.1 Comment Line.
    • 3.2.2 Initial Line.
    • 3.2.3 Continuation Line.
  • 3.3 Statements
  • 3.4 Statement Labels
  • 3.5 Order of Statements and Lines
  • 3.6 Normal Execution Sequence and Transfer of Control
• 4 DATA TYPES AND CONSTANTS
  • 4.1 Data Types
    • 4.1.1 Data Type of a Name.
    • 4.1.2 Type Rules for Data and Procedure Identifiers.
    • 4.1.3 Data Type Properties.
  • 4.2 Constants
    • 4.2.1 Data Type of a Constant.
    • 4.2.2 Blanks in Constants.
    • 4.2.3 Arithmetic Constants.
      • 4.2.3.1 Signs of Constants.
  • 4.3 Integer Type
    • 4.3.1 Integer Constant.
  • 4.4 Real Type
    • 4.4.1 Basic Real Constant.
    • 4.4.2 Real Exponent.
    • 4.4.3 Real Constant.
  • 4.5 Double Precision Type
    • 4.5.1 Double Precision Exponent.
    • 4.5.2 Double Precision Constant.
  • 4.6 Complex Type
    • 4.6.1 Complex Constant.
  • 4.7 Logical Type
    • 4.7.1 Logical Constant.
  • 4.8 Character Type
    • 4.8.1 Character Constant.
• 5 ARRAYS AND SUBSTRINGS
  • 5.1 Array Declarator
    • 5.1.1 Form of an Array Declarator.
      • 5.1.1.1 Form of a Dimension Declarator.
      • 5.1.1.2 Value of Dimension Bounds.
    • 5.1.2 Kinds and Occurrences of Array Declarators.
      • 5.1.2.1 Actual Array Declarator.
      • 5.1.2.2 Dummy Array Declarator.
  • 5.2 Properties of an Array
    • 5.2.1 Data Type of an Array and an Array Element.
    • 5.2.2 Dimensions of an Array.
    • 5.2.3 Size of an Array.
    • 5.2.4 Array Element Ordering.
    • 5.2.5 Array Storage Sequence.
  • 5.3 Array Element Name
  • 5.4 Subscript
    • 5.4.1 Form of a Subscript.
    • 5.4.2 Subscript Expression.
    • 5.4.3 Subscript Value.
  • 5.5 Dummy and Actual Arrays
    • 5.5.1 Adjustable Arrays and Adjustable Dimensions.
  • 5.6 Use of Array Names
  • 5.7 Character Substring
    • 5.7.1 Substring Name.
    • 5.7.2 Substring Expression.
• 6 EXPRESSIONS
  • 6.1 Arithmetic Expressions
    • 6.1.1 Arithmetic Operators.
    • 6.1.2 Form and Interpretation of Arithmetic Expressions.
      • 6.1.2.1 Primaries.
      • 6.1.2.2 Factor.
      • 6.1.2.3 Term.
      • 6.1.2.4 Arithmetic Expression.
    • 6.1.3 Arithmetic Constant Expression.
      • 6.1.3.1 Integer Constant Expression.
    • 6.1.4 Type and Interpretation of Arithmetic Expressions.
    • 6.1.5 Integer Division.
  • 6.2 Character Expressions
    • 6.2.1 Character Operator.
    • 6.2.2 Form and Interpretation of Character Expressions.
      • 6.2.2.1 Character Primaries.
      • 6.2.2.2 Character Expression.
    • 6.2.3 Character Constant Expression.
  • 6.3 Relational Expressions
    • 6.3.1 Relational Operators.
    • 6.3.2 Arithmetic Relational Expression.
    • 6.3.3 Interpretation of Arithmetic Relational Expressions.
    • 6.3.4 Character Relational Expression.
    • 6.3.5 Interpretation of Character Relational Expressions.
  • 6.4 Logical Expressions
    • 6.4.1 Logical Operators.
    • 6.4.2 Form and Interpretation of Logical Expressions.
      • 6.4.2.1 Logical Primaries.
      • 6.4.2.2 Logical Factor.
      • 6.4.2.3 Logical Term.
      • 6.4.2.4 Logical Disjunct.
      • 6.4.2.5 Logical Expression.
    • 6.4.3 Value of Logical Factors, Terms, Disjuncts, and Expressions.
    • 6.4.4 Logical Constant Expression.
  • 6.5 Precedence of Operators
    • 6.5.1 Summary of Interpretation Rules.
  • 6.6 Evaluation of Expressions
    • 6.6.1 Evaluation of Operands.
    • 6.6.2 Order of Evaluation of Functions.
    • 6.6.3 Integrity of Parentheses.
    • 6.6.4 Evaluation of Arithmetic Expressions.
    • 6.6.5 Evaluation of Character Expressions.
    • 6.6.6 Evaluation of Relational Expressions.
    • 6.6.7 Evaluation of Logical Expressions.
  • 6.7 Constant Expressions
• 7 EXECUTABLE AND NONEXECUTABLE STATEMENT CLASSIFICATION
  • 7.1 Executable Statements
  • 7.2 Nonexecutable Statements
• 8 SPECIFICATION STATEMENTS
  • 8.1 DIMENSION Statement
  • 8.2 EQUIVALENCE Statement
    • 8.2.1 Form of an EQUIVALENCE Statement.
    • 8.2.2 Equivalence Association.
    • 8.2.3 Equivalence of Character Entities.
    • 8.2.4 Array Names and Array Element Names.
    • 8.2.5 Restrictions on EQUIVALENCE Statements.
  • 8.3 COMMON Statement
    • 8.3.1 Form of a COMMON Statement.
    • 8.3.2 Common Block Storage Sequence.
    • 8.3.3 Size of a Common Block.
    • 8.3.4 Common Association.
    • 8.3.5 Differences between Named Common and Blank Common.
    • 8.3.6 Restrictions on Common and Equivalence.
  • 8.4 Type-Statements
    • 8.4.1 INTEGER, REAL, DOUBLE PRECISION, COMPLEX, and LOGICAL Type-Statements.
    • 8.4.2 CHARACTER Type-Statement.
  • 8.5 IMPLICIT Statement
  • 8.6 PARAMETER Statement
  • 8.7 EXTERNAL Statement
  • 8.8 INTRINSIC Statement
  • 8.9 SAVE Statement
• 9 DATA STATEMENT
  • 9.1 Form of a DATA Statement
  • 9.2 DATA Statement Restrictions
  • 9.3 Implied-DO in a DATA Statement
  • 9.4 Character Constant in a DATA Statement
• 10 ASSIGNMENT STATEMENT
  • 10.1 Arithmetic Assignment Statement
  • 10.2 Logical Assignment Statement
  • 10.3 Statement Label Assignment (ASSIGN) Statement
  • 10.4 Character Assignment Statement
• 11 CONTROL STATEMENTS
  • 11.1 Unconditional GO TO Statement
  • 11.2 Computed GO TO Statement
  • 11.3 Assigned GO TO Statement
  • 11.4 Arithmetic IF Statement
  • 11.5 Logical IF Statement
  • 11.6 Block IF Statement
    • 11.6.1 IF-Level.
    • 11.6.2 IF-Block.
    • 11.6.3 Execution of a Block IF Statement.
  • 11.7 ELSE IF Statement
    • 11.7.1 ELSE IF-Block.
    • 11.7.2 Execution of an ELSE IF Statement.
  • 11.8 ELSE Statement
    • 11.8.1 ELSE-Block.
    • 11.8.2 Execution of an ELSE Statement.
  • 11.9 END IF Statement
  • 11.10 DO Statement
    • 11.10.1 Range of a DO-Loop.
    • 11.10.2 Active and Inactive DO-Loops.
    • 11.10.3 Executing a DO Statement.
    • 11.10.4 Loop Control Processing.
    • 11.10.5 Execution of the Range.
    • 11.10.6 Terminal Statement Execution.
    • 11.10.7 Incrementation Processing.
    • 11.10.8 Transfer into the Range of a DO-Loop.
  • 11.11 CONTINUE Statement
  • 11.12 STOP Statement
  • 11.13 PAUSE Statement
  • 11.14 END Statement
• 12 INPUT/OUTPUT STATEMENTS
  • 12.1 Records
    • 12.1.1 Formatted Record.
    • 12.1.2 Unformatted Record.
    • 12.1.3 Endfile Record.
  • 12.2 Files
    • 12.2.1 File Existence.
    • 12.2.2 File Properties.
    • 12.2.3 File Position.
    • 12.2.4 File Access.
      • 12.2.4.1 Sequential Access.
      • 12.2.4.2 Direct Access.
    • 12.2.5 Internal Files.
      • 12.2.5.1 Internal File Properties.
      • 12.2.5.2 Internal File Restrictions.
  • 12.3 Units
    • 12.3.1 Unit Existence.
    • 12.3.2 Connection of a Unit.
    • 12.3.3 Unit Specifier and Identifier.
  • 12.4 Format Specifier and Identifier
  • 12.5 Record Specifier
  • 12.6 Error and End-of-File Conditions
  • 12.7 Input/Output Status, Error, and End-of-File Specifiers
    • 12.7.1 Error Specifier.
    • 12.7.2 End-of-File Specifier.
  • 12.8 READ, WRITE, and PRINT Statements
    • 12.8.1 Control Information List.
    • 12.8.2 Input/Output List.
      • 12.8.2.1 Input List Items.
      • 12.8.2.2 Output List Items.
      • 12.8.2.3 Implied-DO List.
  • 12.9 Execution of a Data Transfer Input/Output Statement
    • 12.9.1 Direction of Data Transfer.
    • 12.9.2 Identifying a Unit.
    • 12.9.3 Establishing a Format.
    • 12.9.4 File Position Prior to Data Transfer.
      • 12.9.4.1 Sequential Access.
      • 12.9.4.2 Direct Access.
    • 12.9.5 Data Transfer.
      • 12.9.5.1 Unformatted Data Transfer.
      • 12.9.5.2 Formatted Data Transfer.
        • 12.9.5.2.1 Using a Format Specification.
        • 12.9.5.2.2 List-Directed Formatting.
        • 12.9.5.2.3 Printing of Formatted Records.
    • 12.9.6 File Position After Data Transfer.
    • 12.9.7 Input/Output Status Specifier Definition.
  • 12.10 Auxiliary Input/Output Statements
    • 12.10.1 OPEN Statement.
      • 12.10.1.1 Open of a Connected Unit.
    • 12.10.2 CLOSE Statement.
      • 12.10.2.1 Implicit Close at Termination of Execution.
    • 12.10.3 INQUIRE Statement.
      • 12.10.3.1 INQUIRE by File.
      • 12.10.3.2 INQUIRE by Unit.
      • 12.10.3.3 Inquiry Specifiers.
    • 12.10.4 File Positioning Statements.
      • 12.10.4.1 BACKSPACE Statement.
      • 12.10.4.2 ENDFILE Statement.
      • 12.10.4.3 REWIND Statement.
  • 12.11 Restrictions on Function References and List Items
  • 12.12 Restriction on Input/Output Statements
• 13 FORMAT SPECIFICATION
  • 13.1 Format Specification Methods
    • 13.1.1 FORMAT Statement.
    • 13.1.2 Character Format Specification.
  • 13.2 Form of a Format Specification
    • 13.2.1 Edit Descriptors.
  • 13.3 Interaction Between Input/Output List and Format
  • 13.4 Positioning by Format Control
  • 13.5 Editing
    • 13.5.1 Apostrophe Editing.
    • 13.5.2 H Editing.
    • 13.5.3 Positional Editing.
      • 13.5.3.1 T, TL, and TR Editing.
      • 13.5.3.2 X Editing.
    • 13.5.4 Slash Editing.
    • 13.5.5 Colon Editing.
    • 13.5.6 S, SP, and SS Editing.
    • 13.5.7 P Editing.
      • 13.5.7.1 Scale Factor.
    • 13.5.8 BN and BZ Editing.
    • 13.5.9 Numeric Editing.
      • 13.5.9.1 Integer Editing.
      • 13.5.9.2 Real and Double Precision Editing.
        • 13.5.9.2.1 F Editing.
        • 13.5.9.2.2 E and D Editing.
        • 13.5.9.2.3 G Editing.
        • 13.5.9.2.4 Complex Editing.
    • 13.5.10 L Editing.
    • 13.5.11 A Editing.
  • 13.6 List-Directed Formatting
    • 13.6.1 List-Directed Input.
    • 13.6.2 List-Directed Output.
• 14 MAIN PROGRAM
  • 14.1 PROGRAM Statement
  • 14.2 Main Program Restrictions
• 15 FUNCTIONS AND SUBROUTINES
  • 15.1 Categories of Functions and Subroutines
    • 15.1.1 Procedures.
    • 15.1.2 External Functions.
    • 15.1.3 Subroutines.
    • 15.1.4 Dummy Procedure.
  • 15.2 Referencing a Function
    • 15.2.1 Form of a Function Reference.
    • 15.2.2 Execution of a Function Reference.
  • 15.3 Intrinsic Functions
    • 15.3.1 Specific Names and Generic Names.
    • 15.3.2 Referencing an Intrinsic Function.
    • 15.3.3 Intrinsic Function Restrictions.
  • 15.4 Statement Function
    • 15.4.1 Form of a Statement Function Statement.
    • 15.4.2 Referencing a Statement Function.
    • 15.4.3 Statement Function Restrictions.
  • 15.5 External Functions
    • 15.5.1 Function Subprogram and FUNCTION Statement.
    • 15.5.2 Referencing an External Function.
      • 15.5.2.1 Execution of an External Function Reference.
      • 15.5.2.2 Actual Arguments for an External Function.
    • 15.5.3 Function Subprogram Restrictions.
  • 15.6 Subroutines
    • 15.6.1 Subroutine Subprogram and SUBROUTINE Statement.
    • 15.6.2 Subroutine Reference.
      • 15.6.2.1 Form of a CALL Statement.
      • 15.6.2.2 Execution of a CALL Statement.
      • 15.6.2.3 Actual Arguments for a Subroutine.
    • 15.6.3 Subroutine Subprogram Restrictions.
  • 15.7 ENTRY Statement
    • 15.7.1 Form of an ENTRY Statement.
    • 15.7.2 Referencing External Procedure by Entry Name.
    • 15.7.3 Entry Association.
    • 15.7.4 ENTRY Statement Restrictions.
  • 15.8 RETURN Statement
    • 15.8.1 Form of a RETURN Statement.
    • 15.8.2 Execution of a RETURN Statement.
    • 15.8.3 Alternate Return.
    • 15.8.4 Definition Status.
  • 15.9 Arguments and Common Blocks
    • 15.9.1 Dummy Arguments.
    • 15.9.2 Actual Arguments.
    • 15.9.3 Association of Dummy and Actual Arguments.
      • 15.9.3.1 Length of Character Dummy and Actual Arguments.
      • 15.9.3.2 Variables as Dummy Arguments.
      • 15.9.3.3 Arrays as Dummy Arguments.
      • 15.9.3.4 Procedures as Dummy Arguments.
      • 15.9.3.5 Asterisks as Dummy Arguments.
      • 15.9.3.6 Restrictions on Association of Entities.
    • 15.9.4 Common Blocks.
  • 15.10 Table of Intrinsic Functions
    • 15.10.1 Restrictions on Range of Arguments and Results.
• 16 BLOCK DATA SUBPROGRAM
  • 16.1 BLOCK DATA Statement
  • 16.2 Block Data Subprogram Restrictions
• 17 ASSOCIATION AND DEFINITION
  • 17.1 Storage and Association
    • 17.1.1 Storage Sequence.
    • 17.1.2 Association of Storage Sequences.
    • 17.1.3 Association of Entities.
  • 17.2 Events That Cause Entities to Become Defined
  • 17.3 Events That Caused Entities to Become Undefined
• 18 SCOPES AND CLASSES OF SYMBOLIC NAMES
  • 18.1 Scope of Symbolic Names
    • 18.1.1 Global Entities.
      • 18.1.1.1 Classes of Global Entities.
    • 18.1.2 Local Entities.
      • 18.1.2.1 Classes of Local Entities.
  • 18.2 Classes of Symbolic Names
    • 18.2.1 Common block.
    • 18.2.2 External Function.
    • 18.2.3 Subroutine.
    • 18.2.4 Main Program.
    • 18.2.5 Block Data Subprogram.
    • 18.2.6 Array.
    • 18.2.7 Variable.
    • 18.2.8 Constant.
    • 18.2.9 Statement Function.
    • 18.2.10 Intrinsic Function.
    • 18.2.11 Dummy Procedure.

Appendix A: Criteria, conflicts, and portability

• 19 Criteria
• 20 Conflicts with ANSI X3.9-1966
• 21 Standard Items That Inhibit Portability
• 22 Recommendation for Enhancing Portability

  Appendix B: Section notes

• 23 Section 1 Notes
• 24 Section 2 Notes
• 25 Section 3 Notes
• 26 Section 4 Notes
• 27 Section 5 Notes
• 28 Section 6 Notes
• 29 Section 7 Notes
• 30 Section 8 Notes
• 31 Section 9 Notes
• 32 Section 10 Notes
• 33 Section 11 Notes
• 34 Section 12 Notes
• 35 Section 13 Notes
• 36 Section 14 Notes
• 37 Section 15 Notes
• 38 Section 16 Notes
• 39 Section 17 Notes
• 40 Section 18 Notes

  Appendix C: Hollerith

• 41 Hollerith Data Type
• 42 Hollerith Constant
• 43 Restrictions on Hollerith Constants
• 44 Hollerith Constant
• 45 Hollerith Format Specification
• 46 A Editing of Hollerith Data
• 47 Hollerith Constant in a Subroutine Reference

  Appendix D: Subset Overview

• 48 Background
• 49 Criteria
  • 49.1 Full Language.
  • 49.2 Subset Language.
• 50 Summary of Subset Differences
  • 50.1 Section 1: Introduction.
  • 50.2 Section 2: FORTRAN Terms and Concepts.
  • 50.3 Section 3: Characters, Lines, and Execution Sequence.
  • 50.4 Section 4: Data Types and Constants.
  • 50.5 Section 5: Arrays and Substrings.
  • 50.6 Section 6: Expressions.
  • 50.7 Section 7: Executable and Nonexecutable Statement Classification.
  • 50.8 Section 8: Specification Statements.
  • 50.9 Section 9: DATA Statement.
  • 50.10 Section 10: Assignment Statements.
  • 50.11 Section 11: Control Statements.
  • 50.12 Section 12: Input/Output Statements.
  • 50.13 Section 13: Format Specification.
  • 50.14 Section 14: Main Program.
  • 50.15 Section 15: Functions and Subroutines.
  • 50.16 Section 16: Block Data Subprogram.
  • 50.17 Section 17: Association and Definition.
  • 50.18 Section 18: Scope and Classes of Symbolic Names.
  • 50.19 Section 1 to 18: Character Type.
    • 50.19.1 Character Features in the Subset.
    • 50.19.2 Character Features Not in the Subset.
• 51 Subset Conformance.
  • 51.1 Subset Processor Conformance.
  • 51.2 Subset Program Performance.

    Appendix E: Fortran Statements

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