Q11697: Integer "Overflow" Is Not Trapped without /D Debug Switch
Article: Q11697 Product(s): See article Version(s): 1.00 1.01 1.02 2.00 2.01 3.00 4.00 4.00b 4.50 Operating System(s): MS-DOS Keyword(s): ENDUSER | b_basiccom | mspl13_basic Last Modified: 20-JUL-1989 The following program returns the error "Overflow in line 20 of module at address xxxx:xxxx" when compiled with the /D switch: 10 x% = 129 20 print 256 * x% 30 end If the sample program is compiled without the /D switch, no error is reported, but an incorrect (negative) value is returned. Forcing "256" to single precision by using 256! or 256.0 will eliminate the overflow error. "256" is an integer, and the result of 129 times 256 is greater than 32,767, which is the highest integer allowed. This information applies to Microsoft QuickBASIC Versions 1.00, 1.01, 1.02, 2.00, 2.01, 3.00, 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. These compilers don't handle type coercion, nor do they check for overflow unless the program was compiled with the /D switch.
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