{"id":1717,"date":"2016-01-16T00:01:20","date_gmt":"2016-01-16T08:01:20","guid":{"rendered":"http:\/\/c-for-dummies.com\/blog\/?p=1717"},"modified":"2016-01-17T12:05:58","modified_gmt":"2016-01-17T20:05:58","slug":"give-me-a-break","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=1717","title":{"rendered":"Give Me a break<\/em>"},"content":{"rendered":"

I received an email question recently about the power of the break<\/em> keyword. The answer to the question is that you can only break out of the current loop or switch-case<\/em> structure. Even in a nested loop, or a switch-case<\/em> structure within a loop, break<\/em> affects only the current element.
\n
\nSpecifically, the reader wanted to know if a break<\/em> inside switch-case<\/em> structure would also halt the while<\/em> loop if the structure were inside the loop. The answer is no.<\/p>\n

This type of while<\/em>\/switch-case<\/em> construction is common in many programs. I use it frequently in my code. Sometimes I use:<\/p>\n

while(1)<\/code><\/pre>\n
But more frequently I use:<\/p>\n
while(!done)<\/code><\/pre>\n
Where done<\/code> is a boolean value, either TRUE (1) or FALSE (0).<\/p>\n
The switch-case<\/em> structure inside the while<\/em> loop examines input. Each case<\/em> part of the structure deals with a keypress or some other condition. One of the case<\/em> items handles the loop’s exit condition. For example:<\/p>\n
\r\ncase 'q':\r\ncase 'Q':\r\n     done = TRUE;\r\n     break;<\/pre>\n
Above, on the q<\/code> or Q<\/code> input, the done<\/code> variable is set to TRUE. The break<\/em> statement exits the switch-case<\/em> structure, but not the while<\/em> loop. That loop terminates because the value of done<\/code> is now TRUE.<\/p>\n
For an endless while<\/em> loop, some other condition must be set, because you need a break<\/em> statement outside the switch-case<\/em> structure to terminate the loop.<\/p>\n
The following code example shows nested while<\/em> loops. The break<\/em> statements affects only the current loop:<\/p>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n    int x = 10;\r\n\r\n    puts(\"main() function\");\r\n    while(x)\r\n    {\r\n        puts(\"First while loop\");\r\n        while(x)\r\n        {\r\n            puts(\"\\tSecond while loop\");\r\n            x--;\r\n            if(x<8)\r\n                break;\r\n        }\r\n        if(x<5)\r\n            break;\r\n    }\r\n    puts(\"Back in the main() function\");\r\n\r\n    return(0);\r\n}<\/pre>\n
The output shows how the break<\/em> statement at Line 16 in the inner loop doesn't cancel the outer while<\/em> loop. Only the break<\/em> statement at Line 19 does that. Here is the output:<\/p>\n
\r\nmain() function\r\nFirst while loop\r\n\tSecond while loop\r\n\tSecond while loop\r\n\tSecond while loop\r\nFirst while loop\r\n\tSecond while loop\r\nFirst while loop\r\n\tSecond while loop\r\nFirst while loop\r\n\tSecond while loop\r\nBack in the main() function<\/code><\/pre>\n
One more thing about the break<\/em> keyword: It can dwell only within a loop or switch-case<\/em> structure. The compiler generates an error if you stick a rogue break<\/em> in a function. In other words, you can't use break<\/em> to exit a function or terminate a program.<\/p>\n","protected":false},"excerpt":{"rendered":"
A break<\/em> statement affects only the current loop or switch-case<\/em> structure. 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-1717","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\/1717","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=1717"}],"version-history":[{"count":5,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1717\/revisions"}],"predecessor-version":[{"id":1746,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1717\/revisions\/1746"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1717"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1717"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1717"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}