{"id":314,"date":"2013-10-05T00:01:35","date_gmt":"2013-10-05T08:01:35","guid":{"rendered":"http:\/\/c-for-dummies.com\/blog\/?p=314"},"modified":"2013-10-12T07:37:15","modified_gmt":"2013-10-12T15:37:15","slug":"conversion-character-mania-text-output","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=314","title":{"rendered":"Conversion Character Mania: Text Output"},"content":{"rendered":"

The printf()<\/em> function’s conversion characters %s<\/code> and %c<\/code> seem to be rather straightforward. Or are they?
\n
\nFirst the easy one: To output a single character of text, use %c<\/code>. That conversion character has no options, settings, or optional detritus that can be wedged between the %<\/code> and the c<\/code>. Simple.<\/p>\n

The %s<\/code> conversion character displays strings of text. The entire string is displayed, from the start to the character before the terminating null, character \\0<\/code>. That’s how %s<\/code> is used most often, but it’s not the limits of how you can format a string of text for output.<\/p>\n

\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n    char string[] = \"spatula\";\r\n\r\n    printf(\"%s\\n\",string);\r\n    printf(\"%12s\\n\",string);\r\n    printf(\"%-12s\\n\",string);\r\n    printf(\"%12.3s\\n\",string);\r\n    printf(\"%-12.3s\\n\",string);\r\n\r\n    return(0);\r\n}<\/pre>\n
If you’ve messed with the %s<\/code> conversion character (as shown in my books), then you probably have used some of the examples shown in the above code. Most frequently, %12s<\/code> and %-12s<\/code>. Both limit output to a span of 12 characters; the -<\/code> sign left-justifies the output. These are the same width and alignment options available for formatting numeric output.<\/p>\n
What may seem odd to you is the .3<\/code> option. That’s the precision setting, which has a unique effect on strings. Here’s the program’s output:<\/p>\n
<\/p>\n
spatula\r\n     spatula\r\nspatula     \r\n         spa\r\nspa        <\/pre>\n
<\/code><\/p>\n
In the first line %s<\/code> outputs the entire string.<\/p>\n
The second uses %12s<\/code> to right-justify the output within a width of 12 characters. As with numeric output, if the string is longer than 12 characters, the entire string is displayed; no justification.<\/p>\n
The third example uses %-12s<\/code> to left-justify output within a width of 12 characters. When the string is longer than the width value, no justification is used.<\/p>\n
The fourth and fifth examples add a period and a second value, .3<\/code>. The effect this “precision” value is to truncate the entire string to the number of characters specified.<\/p>\n
So the conversion character %12.3s<\/code> sets output to a 12 character width and truncates output to only the first three characters of the string. The output is right-justified:<\/p>\n
<\/p>\n
         spa<\/pre>\n
<\/code><\/p>\n
The conversion character %-12.3s<\/code> sets output to a 12 character width, left-justified, and truncates the string to the first 3 characters:<\/p>\n
<\/p>\n
spa<\/pre>\n
<\/code><\/p>\n
The truncating doesn’t affect the string itself, only the output.<\/p>\n
Unlike numeric conversion characters, the +<\/code> and 0<\/code> prefix before the width value aren’t allowed for %s<\/code>. If you want that sort of output, you’ll have to code it yourself.<\/p>\n
Next lesson<\/a> I wrap up my Conversion Character Mania series with the rest of the lot not yet covered.<\/p>\n","protected":false},"excerpt":{"rendered":"
Conversion character choices for displaying characters and strings of text are, thankfully, not that complex. Well, that is unless you want them to be. 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-314","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\/314","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=314"}],"version-history":[{"count":8,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/314\/revisions"}],"predecessor-version":[{"id":359,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/314\/revisions\/359"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=314"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=314"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=314"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}