{"id":7287,"date":"2025-12-13T00:01:27","date_gmt":"2025-12-13T08:01:27","guid":{"rendered":"https:\/\/c-for-dummies.com\/blog\/?p=7287"},"modified":"2025-12-20T09:32:13","modified_gmt":"2025-12-20T17:32:13","slug":"dumping-the-screen-in-w-i-d-e-color","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=7287","title":{"rendered":"Dumping the Screen in W-I-D-E Color"},"content":{"rendered":"

Updating the hexdump<\/em> utility with color is good, but adding wide characters for output is even better. From last week’s Lesson<\/a>, I’m adding wide character output to generate codes for non-printing ASCII values 0 through 31 and 127.
\n
\nI cover wide character output in a series of posts<\/a> from 2017. The key is to set the locale, then use the wide character functions for input and output. Though these directions seem easy, it took me two tries to perfect the output.<\/p>\n

My first attempt uses wide character output functions, as well as “long” strings and character values:<\/p>\n

2025_12_13-Lesson-a.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n#include <locale.h>\r\n#include <wchar.h>\r\n\r\n#define RED \"\\e[31m\"\r\n#define NORMAL \"\\e[m\"\r\n\r\nint main()\r\n{\r\n    wchar_t chw;\r\n\r\n    \/* set the local for wide characters *\/<\/span>\r\n    setlocale(LC_CTYPE,\"UTF-8\");\r\n\r\n    for( chw=0; chw<=127; chw++ )\r\n    {\r\n        wprintf(L\"%02X %03d \",chw,chw);\r\n        if( chw<32 )\r\n            wprintf(L\"%s%lc%s\",RED,chw+L'@',NORMAL);\r\n        else if( chw==127 )\r\n            wprintf(L\"%s%lc%s\",RED,9249,NORMAL);\r\n        else\r\n            putwchar(chw);\r\n        putwchar(L'\\n');\r\n    }\r\n    return 0;\r\n}<\/pre>\n
The definitions for the ANSI RED<\/code> and NORMAL<\/code> codes don’t need to be long strings. I tried declaring them as such originally, but the output was weird. So they’re coded as standard ASCII strings.<\/p>\n
Wide character (wchar_t<\/em>) variable chw<\/code> is used for output and as the looping counter.<\/p>\n
The setlocale()<\/em> function sets the character type as UTF-8: setlocale(LC_CTYPE,\"UTF-8\");<\/code><\/p>\n
The wprintf()<\/em> function outputs each line of text. The format string is prefixed with an L<\/code> to indicate a wide string. For values 0 through 32, the character output is chw+L'@'<\/code>. The L<\/code> prefix sets a wide character, which is the value of chw<\/code> plus @<\/code>. For the value 127, Unicode character 9249 is output (U-2421 or ␡).<\/p>\n
The putwchar()<\/em> function outputs single wide characters; the wide newline character is prefixed with an L<\/code>: L'\\n'<\/code><\/p>\n
Here’s the program’s truncated output:<\/p>\n
00 000 @<\/span>
\n01 001 A<\/span>
\n02 002 B<\/span>
\n03 003 C<\/span>
\n04 004 D<\/span>
\n05 005 E<\/span>
\n06 006 F<\/span>
\n07 007 G<\/span>
\n...
\n78 120 x
\n79 121 y
\n7A 122 z
\n7B 123 {
\n7C 124 |
\n7D 125 }
\n7E 126 ~
\n7F 127 DEL<\/span><\/code><\/p>\n
The control codes are output using their letter equivalents color-coded RED: @<\/span> for Ctrl+@, A<\/span> for Ctrl+A, and so on.<\/p>\n
Curiously, the program generates multiple characters for code U-2421: DEL<\/span> instead of ␡. This behavior is considered normal. In fact, I updated the code, replacing Line 18 with the following:<\/p>\n
wprintf(L\"%s%lc%s\",RED,chw+9216,NORMAL);<\/code><\/p>\n
The result of the expression chw+9216<\/code> generates the following output (first 32 lines):<\/p>\n
00 000 NUL<\/span>
\n01 001 SOH<\/span>
\n02 002 STX<\/span>
\n03 003 ETX<\/span>
\n04 004 EOT<\/span>
\n05 005 ENQ<\/span>
\n06 006 ACK<\/span>
\n07 007 BEL<\/span>
\n08 008 BS<\/span>
\n09 009 HT<\/span>
\n0A 010 LF<\/span>
\n0B 011 VT<\/span>
\n0C 012 FF<\/span>
\n0D 013 CR<\/span>
\n0E 014 SO<\/span>
\n0F 015 SI<\/span>
\n10 016 DLE<\/span>
\n11 017 DC1<\/span>
\n12 018 DC2<\/span>
\n13 019 DC3<\/span>
\n14 020 DC4<\/span>
\n15 021 NAK<\/span>
\n16 022 SYN<\/span>
\n17 023 ETB<\/span>
\n18 024 CAN<\/span>
\n19 025 EM<\/span>
\n1A 026 SUB<\/span>
\n1B 027 ESC<\/span>
\n1C 028 FS<\/span>
\n1D 029 GS<\/span>
\n1E 030 RS<\/span>
\n1F 031 US<\/span><\/code><\/p>\n
Individual characters are output instead of single Unicode characters. Despite their appearance, these are Unicode characters. The problem I discovered is with the setlocale()<\/em> function. To fix the output, the setlocale()<\/em> function must be updated to read:<\/p>\n
setlocale(LC_ALL,\"\");<\/code><\/p>\n
After making this change, the first 32 lines output now look like this:<\/p>\n
00 000 ␀<\/span>
\n01 001 ␁<\/span>
\n02 002 ␂<\/span>
\n03 003 ␃<\/span>
\n04 004 ␄<\/span>
\n05 005 ␅<\/span>
\n06 006 ␆<\/span>
\n07 007 ␇<\/span>
\n08 008 ␈<\/span>
\n09 009 ␉<\/span>
\n0A 010 ␊<\/span>
\n0B 011 ␋<\/span>
\n0C 012 ␌<\/span>
\n0D 013 ␍<\/span>
\n0E 014 ␎<\/span>
\n0F 015 ␏<\/span>
\n10 016 ␐<\/span>
\n11 017 ␑<\/span>
\n12 018 ␒<\/span>
\n13 019 ␓<\/span>
\n14 020 ␔<\/span>
\n15 021 ␕<\/span>
\n16 022 ␖<\/span>
\n17 023 ␗<\/span>
\n18 024 ␘<\/span>
\n19 025 ␙<\/span>
\n1A 026 ␚<\/span>
\n1B 027 ␛<\/span>
\n1C 028 ␜<\/span>
\n1D 029 ␝<\/span>
\n1E 030 ␞<\/span>
\n1F 031 ␟<\/span>
\n...<\/code><\/p>\n
The characters used for the control codes may not look exactly as shown above; the specific format depends on the terminal’s typeface. Regardless, the updated code is found here on GitHub<\/a>.<\/p>\n
Now that I’ve figured out how to represent non-printing ASCII codes, I could update my improved hexdump<\/em> utility, but I still need a way to represent values 128 through 255. I cover this task in next week’s Lesson<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
Wide characters offer more variety when outputting “plain” text. Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-7287","post","type-post","status-publish","format-standard","hentry","category-main"],"_links":{"self":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/7287","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7287"}],"version-history":[{"count":12,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/7287\/revisions"}],"predecessor-version":[{"id":7325,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/7287\/revisions\/7325"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7287"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7287"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7287"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}