what does “layout-compatible with C” mean?

Question

It is said that stl vector is "layout-compatible with C". Where can I find the definition of "layout-compatible with C"?

Answer 1

这意味着，只要向量不为空， &vector.front()将为您提供指向连续对象数组的指针，这些对象可以传递给期望此类数组的C API。

Answer 2

It means that the contents of the vector will be laid out in memory the same way they would be in a C array of the same type. That means that if you have a C function that expects to receive a pointer to an array of some type, you can use a vector and pass the function a pointer to the first element of the vector.