{"id":4671,"date":"2021-03-27T00:01:55","date_gmt":"2021-03-27T07:01:55","guid":{"rendered":"https:\/\/c-for-dummies.com\/blog\/?p=4671"},"modified":"2021-04-03T08:31:35","modified_gmt":"2021-04-03T15:31:35","slug":"options-for-the-strfmon-function","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=4671","title":{"rendered":"Options for the strfmon()<\/em> Function"},"content":{"rendered":"

The strfmon()<\/em> function, introduced in last week’s Lesson<\/a> properly formats a monetary value for specific regions. To unlock the function’s various features, you must understand and use formatting placeholders.
\n
\nThe placeholders used in the strfmon()<\/em> function operate like placeholders used by printf()<\/em> and scanf()<\/em>, though different placeholders are used. Like the printf()<\/em> function’s placeholders, the strfmon()<\/em> placeholders are prefixed by the %<\/code> character, which can be followed by optional characters to set specifics, then a final character to define the placeholder.<\/p>\n

The two common, and most reliable, placeholders are %n<\/code> and %i<\/code>. These set the output for the national and international currencies, respectively:<\/p>\n

2021_03_27-Lesson-a.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n#include <locale.h>\r\n#include <monetary.h>\r\n\r\nint main()\r\n{\r\n    char buffer[32];\r\n    char *r;\r\n\r\n    r = setlocale(LC_ALL,\"en_US.UTF-8\");\r\n    if( r==NULL )\r\n    {\r\n        fprintf(stderr,\"Unable to set locale\\n\");\r\n        return(1);\r\n    }\r\n\r\n    strfmon(buffer,32,\"International format: %i\",359246.80);\r\n    puts(buffer);\r\n    strfmon(buffer,32,\"National format: %n\",359246.80);\r\n    puts(buffer);\r\n\r\n    return(0);\r\n}<\/pre>\n
Here is the output:<\/p>\n
International format: USD 359,246.80
\nNational format: $359,246.80<\/code><\/p>\n
As an aside, under OS X the International format was output as USD359,24z???<\/code>, which is some kinda formatting bug on the Mac. If you’re using a Mac, be aware that the strfmon()<\/em> function may not be properly implemented.<\/p>\n
In fact, be aware that this function may not be properly implemented on any platform. This reason may be why the function isn’t included with the MinGW compiler or why it’s relatively unknown.<\/p>\n
To explore the conversion character options, I concocted a test program. Like my series on printf()<\/em> conversion characters (placeholders)<\/a>, I figured a program that runs through all the options and variations would be keen, both to present how the options are used and their effect on output.<\/p>\n
Here’s how far I got:<\/p>\n
2021_03_27-Lesson-b.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n#include <locale.h>\r\n#include <monetary.h>\r\n\r\nint main()\r\n{\r\n    char buffer[32];\r\n    char *r;\r\n\r\n    r = setlocale(LC_ALL,\"en_US.UTF-8\");\r\n    if( r==NULL )\r\n    {\r\n        fprintf(stderr,\"Unable to set locale\\n\");\r\n        return(1);\r\n    }\r\n\r\n    strfmon(buffer,32,\"Normal: %n\",359246.80);\r\n    puts(buffer);\r\n    strfmon(buffer,32,\"No grouping characters: %^n\",359246.80);\r\n    puts(buffer);\r\n    strfmon(buffer,32,\"No currency symbol: %!n\",359246.80);\r\n    puts(buffer);\r\n    strfmon(buffer,32,\"Left justification: %-30n\",359246.80);\r\n    puts(buffer);\r\n\r\n    return(0);\r\n}<\/pre>\n
The three placeholder options I explored are:<\/p>\n
Line 19, The ^<\/code> character that suppresses the hundreds\/thousands separator.<\/p>\n
Line 21, the !<\/code> character that suppresses the currency symbol.<\/p>\n
Line 23, The -30<\/code> option that should set output width to 30 characters, left-justified.<\/p>\n
Here is the output generated on the Macintosh:<\/p>\n
Normal: $359,246.80
\nNo grouping characters: $359246:??
\nNo currency symbol: 359,246.80
\nLeft justification: 359,246.80<\/code><\/p>\n
And for Ubuntu Linux:<\/p>\n
Normal: $359,246.80
\nNo grouping characters: $359246:?
\nNo currency symbol: 359,246.80
\nLeft justification: 359,246.80<\/code><\/p>\n
Both systems failed on the ^<\/code> no-grouping test, throwing garbage into the string. The left justification item failed as well. While it could be argued that I didn’t properly use the formatting strings, this output was enough to make me distrust the function to the degree that I’d never use it.<\/p>\n
The premise for the strfmon()<\/em> function is interesting and possibly could have value specifically for code you write that’s run in a variety of countries or regions. Alas, the placeholder documentation on the web is weak and confusing. The best documentation I found is from IBM:<\/p>\n
https:\/\/www.ibm.com\/support\/knowledgecenter\/ssw_ibm_i_74\/rtref\/strfmon.htm<\/a><\/p>\n
As long as international conversion isn’t required for your code, my advice is to craft your own monetary output function. A very early Exercise post on this blog<\/a> offers some assistance in formatting output values with hundreds\/thousands separators. The rest is up to you.<\/p>\n","protected":false},"excerpt":{"rendered":"
Like the printf()<\/em> function, strfmon<\/em> has placeholders for formatting a monetary 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-4671","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\/4671","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=4671"}],"version-history":[{"count":6,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4671\/revisions"}],"predecessor-version":[{"id":4707,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4671\/revisions\/4707"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4671"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4671"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4671"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}