{"id":11719,"date":"2022-09-28T08:53:24","date_gmt":"2022-09-28T03:23:24","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-do-i-need-to-do-a-free-on-a-struct-closed\/"},"modified":"2022-09-28T08:53:24","modified_gmt":"2022-09-28T03:23:24","slug":"solved-do-i-need-to-do-a-free-on-a-struct-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-do-i-need-to-do-a-free-on-a-struct-closed\/","title":{"rendered":"[Solved] Do I need to do a free on a struct? [closed]"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-21955683\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"21955683\" data-parentid=\"21955600\" data-score=\"3\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<ol>\n<li>you shall not <code>free()<\/code> instances that have not been allocated through <code>malloc()<\/code>, though it&#8217;s unclear how the instance has been allocated before being given to that function, though it&#8217;s unlikely it&#8217;s been <code>malloc()<\/code>ed as this is C++, which leads me to <em>2.<\/em> ;<\/li>\n<li>you should not <code>free()<\/code> C++ objects, but instead call <code>delete<\/code> that will trigger the destructor on instances of objects ;<\/li>\n<li>instead of using a struct and calling method over it, like in C, you shall instead use a class that builds nicely the object by associating a constructor, a destructor and a few methods that handles the encapsulated data ;<\/li>\n<li>on a more general aspects of things, to answer directly your question, you should release the memory of the objects you create at the same level of function call. <\/li>\n<\/ol>\n<p><em>i.e.<\/em> here&#8217;s how you should handle your instance&#8217;s lifetime:<\/p>\n<pre><code>struct sGroupInfo* foo;\n\/\/ allocate memory to foo\nThread_Restore(foo);\n\/\/ release memory for foo\n<\/code><\/pre>\n<p>so when someone else (which may be you in 6 months) read your code, the object&#8217;s lifetime is explicit. If you really <em>need<\/em> to release the memory for your object in the function, then your function&#8217;s name shall reflect it in some way, so it is clear that after your function call, you can&#8217;t rely on the object being still alive.<\/p>\n<p>edit:<\/p>\n<blockquote>\n<p>Not the pointer passed to this function, just the sCNArr, if I should free it?<\/p>\n<\/blockquote>\n<p>so here&#8217;s your code:<\/p>\n<pre><code>\/\/ you give a pointer to some address in the memory to the function\n\/\/ so basically let's consider that: pComputerName == 0x42\nunsigned __stdcall Thread_Restore(void *pComputerName) {\n\/\/ you allocate one word of memory here that contains NULL, i.e. sCNArr == 0x00\nstruct sGroupInfo *sCNArr = NULL;\n\/\/ then you allocate the value of pComputerName to sCNArr, so sCNArr == 0x42\nsCNArr = (struct sGroupInfo *) pComputerName;\n\n\/\/ \u2026\n\n\/\/ if you free something here, you're deallocating the memory at the address 0x42\n\/\/ which will end up in undefined behaviour and\/or crash if you did not allocate\n\/\/ the memory using malloc\nfree(sCNArr);sCNArr=NULL;\n}\n<\/code><\/pre>\n<p>so I guess you shall not.<\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">1<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Do I need to do a free on a struct? [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] you shall not free() instances that have not been allocated through malloc(), though it&#8217;s unclear how the instance has been allocated before being given to that function, though it&#8217;s unlikely it&#8217;s been malloc()ed as this is C++, which leads me to 2. ; you should not free() C++ objects, but instead call delete that &#8230; <a title=\"[Solved] Do I need to do a free on a struct? [closed]\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-do-i-need-to-do-a-free-on-a-struct-closed\/\" aria-label=\"More on [Solved] Do I need to do a free on a struct? [closed]\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324,1157,458],"class_list":["post-11719","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c","tag-free","tag-struct"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Do I need to do a free on a struct? 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