C++ 从 std:vector 获取数组
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Getting array from std:vector
提问by SkypeMeSM
What is the easiest way of getting a char array from a vector?
从向量中获取字符数组的最简单方法是什么？
The way I am doing is getting a string initialized using vector begin and end iterators, and then getting .c_str() from this string. Are there other efficient methods?
我正在做的方法是使用向量开始和结束迭代器初始化一个字符串，然后从这个字符串中获取 .c_str() 。还有其他有效的方法吗？
回答by econoclast
This was discussed in Scott Meyers' Effective STL, that you can do &vec[0]to get the address of the first element of an std::vector, and since the standard constrains vectors to having contiguous memory, you can do stuff like this.
这在 Scott Meyers 的Effective STL 中进行了讨论，您可以这样做&vec[0]来获取 an 的第一个元素的地址std::vector，并且由于标准将向量限制为具有连续内存，因此您可以执行以下操作。
// some function
void doSomething(char *cptr, int n)
{
}
// in your code
std::vector<char> chars;
if (!chars.empty())
{
doSomething(&chars[0], chars.size());
}
edit: From the comments (thanks casablanca)
编辑：来自评论（感谢卡萨布兰卡）
- be wary about holding pointers to this data, as the pointer can be invalidated if the vector is modified.
- 小心保存指向此数据的指针，因为如果修改向量，则指针可能会失效。
回答by ronag
std::vector<char> chars;
char* char_arr = chars.data(); // &chars[0]
