fpt Reference: CHECK DATA IN COMMON BLOCKS

fpt and WinFPT Reference Manual - Command-line Commands

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CHECK DATA IN COMMON BLOCKS

Syntax:

[DO NOT] CHECK DATA [INITIALISATION] IN COMMON [BLOCKS] [DO NOT] CHECK DATA [INITIALIZATION] IN COMMON [BLOCKS]

Function:

fpt checks:

For COMMON blocks which are initialised by DATA in two or more different sub-programs. Many systems only allow each COMMON block to be initialised in a single sub-program. If the same COMMON block is initialised in two different sub-programs, the program may not link (e.g. Compaq Visual Fortran), or may link without reporting errors, but overwrite some of the data (many Unix systems).
For COMMON blocks with variables which are initialised by DATA other than in BLOCK DATA sub-programs. Many compilers allow variables in COMMON blocks to be initialised by DATA statements of by embedded data in PROGRAM, SUBROUTINE or FUNCTION sub-programs. However, this is an extension to the Fortran standard, and is not universally supported.

A common source of this problem is embedded data in derived TYPE or STRUCTURE declarations. Fields of structures, for example, may be initialised by '/' delimited data written after the field names. The data initialise all records of the structure. Any record which is placed in a COMMON block and which is declared in two or more sub-programs then causes multiple data initialisation of the COMMON block. The command CHECK DATA IN STRUCTURES reports embedded data in structures which are used for records in COMMON blocks.

Where to Use this Command

Operating system command line	Yes
Configuration file, config.fsp	Yes
Specification (fsp) files, *.fsp	Yes
Interactively, to FPT> prompt	Yes
Interactive command files	Yes
Embedded in the Fortran code	Yes

Default

The check is not carried out by default (Note that defaults may be changed in the configuration file).

Examples

The user makes the interactive command:

FPT> check data in common

fpt reports:

Data Initialisation of COMMON Blocks ==================================== COMMON /TERRAIN/ initialised in: -------------------------------- PROGRAM EW3 SUBROUTINE EWINI ------------------------------------------------------------------------------- WARNING Number 2847 Severity 1 (Worst 1) Count 4 One or more COMMON blocks is initialised by DATA in two or more sub-programs ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- WARNING Number 2849 Severity 1 (Worst 1) Count 5 One or more COMMON blocks is initialised by DATA or embeddded DATA outside BLOCK DATA -------------------------------------------------------------------------------