Q58926: Array Storage DGROUP vs. Far Heap Differs in .EXE vs. QB.EXE
Article: Q58926 Product(s): See article Version(s): 4.00 4.00b 4.50 Operating System(s): MS-DOS Keyword(s): ENDUSER | SR# S900112-152 B_BasicCom | mspl13_basic Last Modified: 27-FEB-1990 Arrays can be stored in different places depending on array type and on whether the program is run from an .EXE file or the QB.EXE environment. All nonarray (scalar) variables are always stored in DGROUP. In the QuickBASIC QB.EXE environment, a static array of numeric type or fixed-length-string type must be in a COMMON or COMMON SHARED statement to be allocated in the DGROUP memory area; otherwise it will be stored in the far heap. In an executable file (.EXE), all types of static arrays are always stored in the DGROUP area (which can be referenced with a near address). Dynamic or static arrays of variable-length strings are always stored in DGROUP in both QB.EXE and .EXE programs. This information applies to Microsoft QuickBASIC Versions 4.00, 4.00b, and 4.50 for MS-DOS, and to Microsoft BASIC Compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2. For a complete description of variable storage allocation, please read Pages 32 and 33 of the "Microsoft QuickBASIC 4.0: BASIC Language Reference," or Pages 32 and 33 of the "Microsoft BASIC Compiler 6.0: BASIC Language Reference." DGROUP is also known as the default data segment, or the near data storage area. In summary, array storage in QB.EXE adheres to the following three rules: 1. All $STATIC arrays in COMMON or COMMON SHARED are stored in DGROUP. 2. All arrays of type variable-length string are stored in DGROUP. 3. All other arrays are stored in far addresses. Array storage in .EXE programs adheres to the following three rules: 1. All $STATIC arrays are stored in DGROUP. 2. All $DYNAMIC arrays of variable-length strings are stored in DGROUP. 3. All other $DYNAMIC arrays are stored as far objects in the far heap. Program Example --------------- The program below illustrates the preceding information. DIM ar1(100) AS INTEGER ' REM $STATIC is the default for arrays DIM ar2(100) AS INTEGER ' REM $STATIC is the default for arrays COMMON SHARED ar2() AS INTEGER ' Must be in COMMON in QB.EXE environment to be placed in DGROUP. s$ = "hello" ' this is put into the DGROUP REM $DYNAMIC DIM ar3(100) AS INTEGER PRINT VARSEG(s$), VARSEG(ar1(0)), VARSEG(ar2(0)), VARSEG(ar3(0))
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