{"id":2879,"date":"2018-01-01T00:01:11","date_gmt":"2018-01-01T08:01:11","guid":{"rendered":"http:\/\/c-for-dummies.com\/blog\/?p=2879"},"modified":"2018-01-08T08:12:59","modified_gmt":"2018-01-08T16:12:59","slug":"swapping-strings","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=2879","title":{"rendered":"Swapping Strings"},"content":{"rendered":"

Last month’s Exercise<\/a> was rather silly: Rarely do you need to swap elements between two integer arrays. As Chris pointed out in the Exercise’s comments, “Would it not be easier to just use the array which contains the values you need?” Indeed, it is, which leads up to this month’s Exercise.
\n
\nConsider that you have two arrays:<\/p>\n

\r\nchar *beatles[4] = {\r\n    \"John\", \"Paul\", \"George\", \"Ringo\"\r\n};\r\nchar *stones[4] = {\r\n    \"Mick\", \"Keith\", \"Ronnie\", \"Charlie\"\r\n};<\/pre>\n
These are not string arrays, but pointer arrays. The declaration char *<\/code> defines a pointer, and char *beatles[4]<\/code> references four pointers. The pointers are all preset (in both arrays above) to various strings.<\/p>\n
Indeed, when you see such a string declaration, you must be careful not to manipulate the strings directly. If you do, you experience all sorts of pointer woe, but that’s not the point of this Exercise.<\/p><\/blockquote>\n
Your task is to swap pointers between the two arrays. I would write, “swap strings between the two arrays” (and that’s this post’s title), but what you’re really doing is swapping pointers. In fact, if your solution involves manipulating the strings, you’ll soon discover the ugly truth — but I’ll leave that frustration to you.<\/p>\n
Here’s the rest of the main()<\/em> function for this month’s Exercise:<\/p>\n
\r\nint main()\r\n{\r\n    char *beatles[4] = {\r\n        \"John\", \"Paul\", \"George\", \"Ringo\"\r\n    };\r\n    char *stones[4] = {\r\n        \"Mick\", \"Keith\", \"Ronnie\", \"Charlie\"\r\n    };\r\n\r\n    printf(\"Original arrays:\\n\");\r\n    show_arrays(beatles,stones);\r\n\r\n    swap_arrays(beatles,stones);\r\n\r\n    printf(\"After swap:\\n\");\r\n    show_arrays(beatles,stones);\r\n\r\n    return(0);\r\n}<\/pre>\n
The solution <\/a>is quite similar to last month’s Exercise; you write your own versions of the show_arrays()<\/em> and swap_arrays()<\/em> functions.<\/p>\n","protected":false},"excerpt":{"rendered":"
A quick method exists to swap string elements between two arrays. 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":[3],"tags":[],"class_list":["post-2879","post","type-post","status-publish","format-standard","hentry","category-exercise"],"_links":{"self":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2879","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=2879"}],"version-history":[{"count":5,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2879\/revisions"}],"predecessor-version":[{"id":2935,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2879\/revisions\/2935"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2879"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2879"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2879"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}