[問題] (ptr == NULL) 和 (ptr) 的差別

看板C_and_CPP作者eagle36時間13年前 (2011/04/09 01:14)推噓3(3推 0噓 16→)

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當測試指標的時候常會使用到例如: if (ptr != NULL) { free(ptr); ptr == NULL; } 但是看到一篇文章 Mozilla coding style寫道 https://developer.mozilla.org/En/Mozilla_Coding_Style_Guide - Don't use NULL for pointers. On some systems it's declared as void * and causes a compile warning when assigned to a pointer. Use 0 or nsnull instead. - When testing a pointer, use !myPtr or (myPtr); don't use myPtr != nsnull or myPtr == nsnull. - Do not compare x == PR_TRUE or x == PR_FALSE. Use (x) or (!x) instead. x == PR_TRUE, in fact, is different from if (x)! 我看到 void * 想說是否可攜性有關，例如 16bit or 32bit等等，不過又不是很確定，讓我有些困惑，有人知道為什麼他會這樣寫嗎? -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 123.192.156.151

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tropical72

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