That looks wrong to me because a char is one byte and you've given it two (C2 B1),...

Yeah - when I do a noisy build (and thereby have any warnings displayed) I see the same warning.
I also see warning: unsigned conversion from 'int' to 'unsigned char' changes value from '49841' to '177' [-Woverflow].
Then, when the chr(177) gets written to a text file, it displays as the desired plus-or-minus symbol when viewed in Windows notepad.

In pure Perl, with a combination of chcp 65001 and use open qw/:std :encoding(UTF-8)/;, I can get it to output correctly

Thanks for that - I see exactly the same behaviours with your test.pl as you did.

The mention of codepage 65001 looks to have been the godsend I was looking for.
Using that codepage, this troublesome C library function (in mpc-1.3.x) by the name of "mpcr_out_str", then displays correctly when accessed from the Math::MPC module.

Is there some way I can manipulate the active code page in perl (on windows) without shelling out to chcp ?
I'm thinking that, for Windows only, Math::MPC needs to change the codepage to 65001 before calling this function ... and then it ought also revert the codepage to its original setting immediately after the function has been run.
I guess I should also check to see if 65001 ought only be set when Windows prints to stdout.
Does that sound reasonable ? (I will check this on a range of perls on Windows 7 and Windows 11 anyway.)
Update: Hmmm, a quick check on Windows 7 reveals that changing the codepage is apparently having no effect. Bummer !! (But it's getting late over here, and will have to wait until I've had some sleep, before checking further.)

Thanks ever so much for the responses. Things are now a little clearer.

Cheers,
Rob

In reply to Re^2: Encoding problem with function in C library by syphilis
in thread Encoding problem with function in C library by syphilis

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.