Hackers Guide to Visual FoxPro 7.0

2017-07-07 02:10:07

FCount(), FldCount(), Field(), FSize()

FCOUNT() and FLDCOUNT() return the number of fields in a table. FIELD() returns the name of a specified field in a table. FSIZE() is confused: It is two different functions, depending on the setting of—ugh!—SET COMPATIBLE. Generally speaking, we avoid these commands altogether, and let AFIELDS() give us all the information at once.

Usage

nFieldCount = FCOUNT( [ cAlias | nWorkarea ] ) nFieldCount = FLDCOUNT( [ cAlias | nWorkarea ] ) cFieldName = FIELD( nField, [ cAlias | nWorkarea ] ) * With SET COMPATIBLE OFF: nFieldSize = FSIZE( cFieldName, [ cAlias | nWorkarea ] ) * With SET COMPATIBLE ON: nFileSize = FSIZE( cFileName )

Parameter	Value	Meaning
cAlias	Character	The alias of the table about which information is returned.
cAlias	Omitted	If nWorkarea is also omitted, use current work area.
nWorkarea	Numeric	The number of the work area containing the table about which information is returned.
nWorkarea	Omitted	If cAlias is also omitted, use current work area.
nFieldCount	Numeric	Number of fields in the specified table.
nField	Numeric	Number of the field to return, based on physical order of the table.
cFieldName	Character	The field's name.
nFieldSize	Numeric	Size of the field (SET COMPATIBLE OFF).
cFileName	Character	The name of the file.
nFileSize	Numeric	Size of the file (SET COMPATIBLE ON).

FCOUNT() and FLDCOUNT() do not report on hidden, system fields (see "DBF, FPT, CDX, DBC—Hike!"). If you use one of them with FSIZE() to try to calculate the size of a table, you'll come out with the wrong number if any of the fields are nullable. You need to use RECSIZE() or AFIELDS() to test for this, and while you're at it, you can use the return value of AFIELDS() for a better FCOUNT() and the sum of the AFIELDS() size values for a better FSIZE().

FLDCOUNT() is a totally undocumented clone of FCOUNT(), added in FoxPro 2.6 as part of the dBase IV compatibility campaign. We recommend you avoid it, if for no other reason than to take pity on the poor soul who has to maintain your code. After all, it might be you.

FIELD() returns the name of the field based on its order within the table. Because fields within a table can be rearranged quite easily, you'll not want to hardcode field-order numbers into your code. Instead, FIELD() could prove valuable in a black-box looping structure where you're scanning for certain field names. However, AFIELDS() provides a lot more information in an easily manipulated array and tends to be the function we prefer to use.

FSIZE() is a horror show. Fox Software and Ashton-Tate each went its own way with this function—it's one of the few that is affected by the dreaded SET COMPATIBLE command. If SET COMPATIBLE is OFF or FOXPLUS, FSIZE() returns the field size of the specified field. If FSIZE() is called with SET COMPATIBLE STUPID, er, we mean, ON or DB4, it returns the size of the specified file. Our advice: Leave COMPATIBLE SMART (FoxPlus) and use ADIR() to get file sizes.

Example

SET COMPATIBLE FOXPLUS USE HOME() + "LABELS" nFieldSize = FSIZE("Name", "Labels") && returns 24 SET COMPATIBLE DB4 nFileSize = FSIZE(HOME()+"Labels") && returns 6622 ? FCOUNT("LABELS") && seven ? FIELD(3, "LABELS") && returns "NAME"

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