{"id":6173,"date":"2023-12-30T00:01:37","date_gmt":"2023-12-30T08:01:37","guid":{"rendered":"https:\/\/c-for-dummies.com\/blog\/?p=6173"},"modified":"2024-01-06T09:51:24","modified_gmt":"2024-01-06T17:51:24","slug":"binary-notation-in-c23","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=6173","title":{"rendered":"Binary Notation in C23"},"content":{"rendered":"

While the C language offers hexadecimal notation and output, it ignores binary. Now with the C 23 standard, binary expression and output is supported.
\n
\nIf you were to guess, what do you think would be the prefix for an integer expressed in binary notation?<\/p>\n

Yep, it’s 0b<\/code>. Simple. Consistent.<\/p>\n

The value 26 expressed in binary for the C23 standard looks like this: 0b11010<\/code><\/p>\n

Here is sample code for C23 that outputs a binary integer value in decimal and hex:<\/p>\n

2023_12_30-Lesson-a.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n    int a = 0b11010;\r\n\r\n    printf(\"Decimal: %d\\n\",a);\r\n    printf(\"Hex: %x\\n\",a);\r\n\r\n    return 0;\r\n}<\/pre>\n
Remember from last week’s Lesson<\/a>, you must specify the -std=c2x<\/code> switch for the compiler to recognize and use the C23 standard. When active, the switch enables the compiler to recognize the 0b11010<\/code> notation and value. Here is the output:<\/p>\n
Decimal: 26
\nHex: 1a<\/code><\/p>\n
The C23 flavor has another binary trick up its sleeve: the tick binary separator. The tick separator isn’t a new C feature. It’s available now with hexadecimal values. With binary notation, however, the tick separator becomes highly useful.<\/p>\n
Programmers often write binary values in clumps of four. These match up with the hex digits 0 through F:<\/p>\n\n\n\n\n\n\n
Binary<\/td>\nHex<\/td>\nBinary<\/td>\nHex<\/td>\nBinary<\/td>\nHex<\/td>\nBinary<\/td>\nHex<\/td>\n<\/tr>\n
0000<\/td>\n0<\/td>\n0100<\/td>\n4<\/td>\n1000<\/td>\n8<\/td>\n1100<\/td>\nc<\/td>\n<\/tr>\n
0001<\/td>\n1<\/td>\n0101<\/td>\n5<\/td>\n1001<\/td>\n9<\/td>\n1101<\/td>\nd<\/td>\n<\/tr>\n
0010<\/td>\n2<\/td>\n0110<\/td>\n6<\/td>\n1010<\/td>\na<\/td>\n1110<\/td>\ne<\/td>\n<\/tr>\n
0011<\/td>\n3<\/td>\n0111<\/td>\n7<\/td>\n1011<\/td>\nb<\/td>\n1111<\/td>\nf<\/td>\n<\/tr>\n<\/table>\n
I’ve written about these tick separators<\/a> before, specifically how they’re used in hexadecimal values. Here’s how they’re useful in binary notation:<\/p>\n
int a = 0b001'1010;<\/code><\/p>\n
The ticks need not be used every four positions, either:<\/p>\n
int a = 0b0'01'10'10;<\/code><\/p>\n
Or even:<\/p>\n
int a = 0b00'11010;<\/code><\/p>\n
How you place the ticks is up to you, but they’re used to separate a long binary value for easy reading.<\/p>\n
The C23 standard also defines the %b<\/code> conversion specification, which is used as a placeholder in a printf()<\/em> or scanf()<\/em> format string to output or accept binary values. So the following statement could be added to the code:<\/p>\n
printf(\"Binary: %b\\n\",a);<\/code><\/p>\n
For some reason, this conversion specification throws a warning when clang-15<\/em> builds the program. Even so, a program is created:<\/p>\n
Decimal: 26
\nHex: 1a
\nBinary: 11010<\/code><\/p>\n
I tested the %b<\/code> placeholder with the following code as well:<\/p>\n
2023_12_30-Lesson-b.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n    int b = 26;\r\n\r\n    printf(\"%b\\n\",b);\r\n\r\n    return 0;\r\n}<\/pre>\n
Again, the warning is generated, but the program produces the proper output:<\/p>\n
11010<\/code><\/p>\n
Feeling saucy, I decided to see whether a width specifier works with the %b<\/code> placeholder. I changed the program’s printf()<\/em> statement to read %8b<\/code>. Here’s the output:<\/p>\n
   11010<\/code><\/p>\n
Yes, the output is 8-characters wide, but I wanted leading zeros. So I updated the code to use %08b<\/code> instead. Here’s the result:<\/p>\n
00011010<\/code><\/p>\n
Pretty cool, especially to this nerd.<\/p>\n
The %b<\/code> placeholder does not work in the scanf()<\/em> function for reading binary input. I figure this feature isn’t implemented for the clang-15<\/em> compiler I’m using. My guess and hope is that it finds its way into a future release of clang<\/em>.<\/p>\n
In next week’s Lesson<\/a> I cover a new C23 data type, precise integers. Happy New Year, everyone!<\/p>\n","protected":false},"excerpt":{"rendered":"
One of the great tricks available in the new C23 standard is the capability to express and output binary values. 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-6173","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\/6173","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=6173"}],"version-history":[{"count":12,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6173\/revisions"}],"predecessor-version":[{"id":6211,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6173\/revisions\/6211"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6173"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6173"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}