{"id":3032,"date":"2018-04-07T00:01:56","date_gmt":"2018-04-07T07:01:56","guid":{"rendered":"http:\/\/c-for-dummies.com\/blog\/?p=3032"},"modified":"2018-04-14T07:57:02","modified_gmt":"2018-04-14T14:57:02","slug":"from-binary-to-string","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=3032","title":{"rendered":"From Binary to String"},"content":{"rendered":"

In my books, I use the binbin()<\/em> function to display binary values. It’s a good way to demonstrate some of the C language’s low-level bitwise functions: The binbin()<\/em> function lets you see the effect of bitwise operations at a binary level, all those ones and zeros.
\n
\nOver the years, I’ve messed with the binbin()<\/em> function. Here’s the current version, which I now call binString()<\/em>:<\/p>\n

\r\nchar *binString(unsigned short n)\r\n{\r\n    static char bin[17];\r\n    int x;\r\n\r\n    for(x=0;x<16;x++)\r\n    {\r\n        bin[x] = n & 0x8000 ? '1' : '0';\r\n        n <<= 1;\r\n    }\r\n    bin[16] = '\\0';\r\n\r\n    return(bin);\r\n}<\/pre>\n
The binString()<\/em> function accepts an unsigned short<\/em> integer as input, variable n<\/code> inside the function. The short<\/em> variable has a bit width of 16, so the string created is 16-characters long. The bin[]<\/code> char<\/em> array holds output string, plus one extra position for the null character, \\0<\/code>, at the end of the string. It’s a static char<\/em> array, so its value is retained after the function call.<\/p>\n
Within the function, a for<\/em> loop processes each bit in value n<\/code>. The binary &<\/code> (AND) operator compares the far left bit with 1 and sets the character ‘1’ or ‘0’ depending on the bit’s value. Value n<\/code> is then shifted left one bit position and the loop continues. The result is a string representing the bit values stored in n<\/code>, which is returned from the function.<\/p>\n
Here is the full code I use to test the binString()<\/em> function:<\/p>\n
\r\n#include <stdio.h>\r\n\r\nchar *binString(unsigned short n)\r\n{\r\n    static char bin[17];\r\n    int x;\r\n\r\n    for(x=0;x<16;x++)\r\n    {\r\n        bin[x] = n & 0x8000 ? '1' : '0';\r\n        n <<= 1;\r\n    }\r\n    bin[16] = '\\0';\r\n\r\n    return(bin);\r\n}\r\n\r\nint main()\r\n{\r\n    unsigned short value;\r\n\r\n    printf(\"Enter an integer value, 0 to 65535: \");\r\n    scanf(\"%hd\",&value);\r\n\r\n    printf(\"Decimal value is %d\\n\",value);\r\n    printf(\"Octal value is %o\\n\",value);\r\n    printf(\"Hexadecimal value is 0x%X\\n\",value);\r\n    printf(\"Binary value is %s\\n\",binString(value));\r\n\r\n    return(0);\r\n}<\/pre>\n
Sample run:<\/p>\n
Enter an integer value, 0 to 65535: 43690\r\nDecimal value is 43690\r\nOctal value is 125252\r\nHexadecimal value is 0xAAAA\r\nBinary value is 1010101010101010<\/code><\/pre>\n
I use the binbin()<\/em> version of the binString()<\/em> function in my book, Beginning Programming with C For Dummies<\/em>, to demonstrate the various bitwise functions in C. The binString()<\/em> function improves upon it by returning a full string, but the result is the same: a string representation of bits. This complements the natural capability of the C language to output decimal, octal, and hexadecimal.<\/p>\n
But what about the other way?<\/p>\n
For example, you can input decimal, octal, and hexadecimal values into a C program, but you can’t input binary.<\/p>\n
The following code accepts hexadecimal input:<\/p>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n    unsigned n;\r\n\r\n    printf(\"Type a hex value: \");\r\n    scanf(\"%x\",&n);\r\n    printf(\"You typed %X, which is %d\\n\",n,n);\r\n\r\n    return(0);\r\n}<\/pre>\n
The %x<\/code> directs the scanf()<\/em> function to read hexadecimal values. Here’s the sample run:<\/p>\n
Type a hex value: AA\r\nYou typed AA, which is 170<\/code><\/pre>\n
You could change the %x<\/code> in the scanf()<\/em> function to %o<\/code> to input octal values or %d<\/code> to input decimal values. What you cannot do, however, is use a %<\/code> placeholder to read in a binary value. That’s a topic I tackle in next week’s Lesson<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
Another look at my binbin()<\/em> function, which displays a value as a binary string. 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-3032","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\/3032","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=3032"}],"version-history":[{"count":5,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3032\/revisions"}],"predecessor-version":[{"id":3062,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3032\/revisions\/3062"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3032"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3032"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3032"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}