{"id":6902,"date":"2025-04-08T00:01:25","date_gmt":"2025-04-08T07:01:25","guid":{"rendered":"https:\/\/c-for-dummies.com\/blog\/?p=6902"},"modified":"2025-04-05T10:50:54","modified_gmt":"2025-04-05T17:50:54","slug":"a-nutty-non-loop-solution","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=6902","title":{"rendered":"A Nutty Non-Loop – Solution"},"content":{"rendered":"

The insane challenge for this month’s Exercise<\/a> is to generate a countdown loop without using any looping functions. And, no, you can’t just use a buncha printf()<\/em> statements to output the values.
\n
\nIf you’ve been reading this blog for any length of time, you probably know that when I use the word “insane” I’m referring to recursion. The inspiration for the exercise is based on the possibility of recursively calling the main()<\/em> function.<\/p>\n

I demonstrated a single recursive call to the main()<\/em> function in a post from several years ago (Stupid main()<\/em> Function Tricks<\/a>). Upon reviewing that old post, I thought about taking the insanity a step further and using recursion in main()<\/em> to output descending values. Here is the result, and my solution:<\/p>\n

2025_04-Exercise.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n\r\nint main(int argc, char *argv[])\r\n{\r\n    if( argc==11 )\r\n        return argc;\r\n    printf(\"%d\\n\",main(argc+1,NULL)-1);\r\n\r\n    return argc;\r\n}<\/pre>\n
The main()<\/em> function calls itself within the printf()<\/em> statement. Its arguments are the values of argc<\/code> (the argument count) plus one and NULL. The NULL is required and valid, but unusable. It doesn’t matter, however, as the countdown is what’s stored in argc<\/code> and what’s eventually output.<\/p>\n
The trick is to get the values to output in reverse order. Therefore, the exit trigger for recursion is argc==11<\/code> — one more than ten. Once triggered, the value of argc<\/code> is returned and output in the printf()<\/em> statement.<\/p>\n
As recursion unwinds, each subsequent argc<\/code> value is output, 9 through 1. The final return argc<\/code> statement sends the last value, 1, to the operating system.<\/p>\n
Here’s a sample run:<\/p>\n
10
\n9
\n8
\n7
\n6
\n5
\n4
\n3
\n2
\n1<\/code><\/p>\n
I hope that your solution also met with success. And if you came up with something different, I’d enjoy seeing it.<\/p>\n","protected":false},"excerpt":{"rendered":"
The insane challenge for this month’s Exercise is to generate a countdown loop without using any looping functions. And, no, you can’t just use a buncha printf() statements to output the values.<\/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-6902","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\/6902","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=6902"}],"version-history":[{"count":5,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6902\/revisions"}],"predecessor-version":[{"id":6925,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6902\/revisions\/6925"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6902"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6902"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6902"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}