是否& s [0]指向std :: string中的连续字符？

本文介绍了是否& s [0]指向std :: string中的连续字符？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我正在进行一些维护工作，并且遇到以下情况：I'm doing some maintenance work and ran across something like the following:std::string s;s.resize( strLength );// strLength is a size_t with the length of a C string in it.memcpy( &s[0], str, strLength );我知道使用& s [0]是安全的，如果它是一个std :: vector，但是这是一个安全使用std :: string？I know using &s[0] would be safe if it was a std::vector, but is this a safe use of std::string?推荐答案 std :: string的分配不保证是连续的C ++ 98/03标准，但C ++ 11强制它。实际上，我和 Herb Sutter 知道不使用连续存储的实现。A std::string's allocation is not guaranteed to be contiguous under the C++98/03 standard, but C++11 forces it to be. In practice, neither I nor Herb Sutter know of an implementation that does not use contiguous storage.请注意，& s [0] 总是保证通过C ++ 11标准工作，即使在0长度字符串的情况下。如果您 str.begin（）或& * str.begin（），但不能保证& s [0] 标准定义 operator [] 为：Notice that the &s[0] thing is always guaranteed to work by the C++11 standard, even in the 0-length string case. It would not be guaranteed if you did str.begin() or &*str.begin(), but for &s[0] the standard defines operator[] as:继续， data（）定义为：（注意范围两端的方括号）(notice the square brackets at both ends of the range) 注意：预标准化C ++ 0x不能保证& s [0] 使用零长度字符串（实际上，它是明确未定义的行为），而这个答案的旧版本解释了这一点;这在以后的标准草案中已经解决，因此答案已相应更新。Notice: pre-standardization C++0x did not guarantee &s[0] to work with zero-length strings (actually, it was explicitly undefined behavior), and an older revision of this answer explained this; this has been fixed in later standard drafts, so the answer has been updated accordingly. 这篇关于是否& s [0]指向std :: string中的连续字符？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！