{"id":2847,"date":"2017-12-08T00:01:22","date_gmt":"2017-12-08T08:01:22","guid":{"rendered":"http:\/\/c-for-dummies.com\/blog\/?p=2847"},"modified":"2017-12-02T11:39:57","modified_gmt":"2017-12-02T19:39:57","slug":"swapping-arrays-solution","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=2847","title":{"rendered":"Swapping Arrays – Solution"},"content":{"rendered":"

The two functions required from this month’s Exercise<\/a> are show_arrays()<\/em> and swap_arrays()<\/em>. They’re not that difficult to code, meaning that you don’t need to use the dratted **<\/code> notation or perform any special tricks. Here’s how I solved the problem:
\n
\nFirst, I used a SIZE<\/code> constant to handle the number of elements in both arrays:<\/p>\n

#define SIZE 5<\/code><\/p>\n

This step isn’t required, but it does allow me flexibility later should both arrays change their number of elements.<\/p>\n

Second, for each function, the values passed are pointers, i.e., the memory address where each array is located. The functions are prototyped similarly:<\/p>\n

void show_arrays(int *y, int *z);
\nvoid swap_arrays(int *y, int *z);<\/code><\/p>\n

Both are void<\/code> functions because they don’t return anything; the arrays are manipulated in memory directly, which is the beauty of using pointers.<\/p>\n

Third, the functions:<\/p>\n

The show_arrays()<\/em> function is necessary because otherwise I’d repeat the same chunk of code in the main()<\/em> function. It uses two for<\/em> loops to display each array’s elements:<\/p>\n

\r\nvoid show_arrays(int *y, int *z)\r\n{\r\n    int x;\r\n\r\n    printf(\"a =\");\r\n    for(x=0;x<SIZE;x++)\r\n        printf(\" %2d\",y[x]);\r\n    putchar('\\n');\r\n    printf(\"b =\");\r\n    for(x=0;x<SIZE;x++)\r\n        printf(\" %2d\",z[x]);\r\n    putchar('\\n');\r\n}<\/pre>\n
The %2d<\/code> placeholder in each printf()<\/em> statement keeps the output looking even between both arrays:<\/p>\n
a =  2  4  6  8 10\r\nb =  1  3  5  7  9<\/code><\/pre>\n
For the swap_arrays()<\/em> function, here’s what I concocted:<\/p>\n
\r\nvoid swap_arrays(int *y, int *z)\r\n{\r\n    int x,temp;\r\n\r\n    for(x=0;x<SIZE;x++)\r\n    {\r\n        temp = y[x];\r\n        y[x] = z[x];\r\n        z[x] = temp;\r\n    }\r\n}<\/pre>\n
All you need to swap elements is a temporary storage int<\/em> variable, temp<\/code>. The value of y[x]<\/code> element is saved to temp<\/code>. Then z[x]<\/code> is placed into y[x]<\/code>. Finally, temp<\/code> is placed into z[x]<\/code>. This loop repeats for each element.<\/p>\n
None of the variables in the function need to be pointers; only the array’s location is passed to the function as a pointer. Within the function, array notation can be used as a substitute. The temp<\/code> variable isn’t a pointer because the array elements are int<\/em> values, not pointers.<\/p>\n
Click here<\/a> to view the final code, which I find quite simple, but still a good exercise.<\/p>\n
If you came up with another solution and the output is solid, congratulations!<\/p>\n","protected":false},"excerpt":{"rendered":"
The two functions required from this month’s Exercise are show_arrays() and swap_arrays(). They’re not that difficult to code, meaning that you don’t need to use the dratted ** notation or perform any special tricks. Here’s how I solved the problem:<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-2847","post","type-post","status-publish","format-standard","hentry","category-solution"],"_links":{"self":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2847","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=2847"}],"version-history":[{"count":4,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2847\/revisions"}],"predecessor-version":[{"id":2865,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2847\/revisions\/2865"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2847"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2847"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2847"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}