Turbo Basic

CHAIN statementFunctionSyntaxRemarksCHAIN invokes a Turbo Basic chain module (created as a .TBC or.EXE file).CHAIN filespecfilespec is a string expression that follows standard DOS namingconventions and represents a Turbo Basic chain module (extension.TBC). If the extension is omitted, .TBC is assumed. Therefore, ifyou want to specify an .EXE file, you must append .EXE to the filename. The variables listed as COMMON in both the current programand the destination program are passed to the destinationprogram.In the testing phase, the calling program must be compiled to an.EXE file, because you can't chain from within Turbo Basic. Thecalled program must be compiled to disk as a chain module (an.EXE or .TBC file).If the arguments to the COMMON statements in the calling programand the called program don't match (for example, floatingpointvariables in one place and integers in another), a run-timeerror occurs.Turbo Basic doesn't support Interpretive BASIC's line numberorientedCHAIN options, including DELETE, MERGE, andCHAIN linenumber. Since you can't specify a line number within adestination chain module, execution always starts at the beginning.RestrictionsDifferencesSee AlsoIn translating a CHAINed system of Interpretive BASIC programsto Turbo Basic, you may find that Turbo Basic's expanded useof memory allows consolidating individual modules into a singleprogram, making chaining unnecessary.CHAINing can only be done when a program is being executedfrom DOS; that is, from an .EXE file. MERGE, DELETE, ALL,and CHAINing to a line number are not supported.In Turbo Basic, CHAINing is done from one compiled program toanother that has been compiled to a .TBC or .EXE file.COMMONTurbo Basic Reference Directory 145