Travis Siegel via fpc-pascal said on Sun, 4 Jun 2023 19:38:44 +0000 > >On 6/4/2023 1:37 PM, Steve Litt via fpc-pascal wrote: >> Henry Vermaak via fpc-pascal said on Fri, 2 Jun 2023 09:38:17 +0100 >> >>> On Fri, 2 Jun 2023 at 01:36, Steve Litt via fpc-pascal >>> <fpc-pascal@lists.freepascal.org> wrote: >>>> fillchar(junkvar, junkvar_size, 'b'); >>>> person := modperson(person, 'Martin'); >>>> person := modperson(person2, 'Maria'); >>> Maybe a typo? (E.g. person2 := modperson(person2, 'Maria')) >>> >>> Henry >> Thanks Henry! >> >> You're right: Changing the second person := to person2 := did just >> what I wanted it to do. >> >> Because returning a local array or string as a function return in C >> leads to horrible intermittents due to the local going out of scope >> and relinquishing the local's stack, which can then be overwritten, >> I added a procedure, a function, and a main program statement which >> each consumed two million bytes of local variables, and the person >> and person2 didn't get overwritten. Very cool. >> >> When I increased the huge local vars to three million bytes, the >> program segfaulted. I figure I just ran it out of stack, but until I >> did, the huge local vars didn't trash the contents of person and >> person2. >> >> Thanks for your help. >> >> SteveT
>Depending on the compiler *not* to overwrite local variables is most >certainly the wrong way to go with this. You really should create >either a global record/object, or use functions to pass around the >information you need. Expecting the operating system to keep local >variables after the area goes out of scope is just begging for errors >later on when the compiler/os treatment of said areas changes. Thanks Travis, This is the info I was asking for. Yeah, passing the local as a function return worked, but because of a horrible experience doing that in C, I was suspicious and leery of actually using that technique. I'll just use new and dispose. Thanks, SteveT Steve Litt Autumn 2022 featured book: Thriving in Tough Times http://www.troubleshooters.com/bookstore/thrive.htm _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
